CA1217851A - Talking depth sounder - Google Patents

Abstract

A B S T R A C T

Apparatus is provided for adapting an analog depth sounder for the calling out of the depth at regular time intervals. In one embodiment, a self-contained adapter module is mounted to the face of the depth sounder so as to cover the depth sounder display, with the module including a transparent plate carrying a detector array and with electronics and speaker carried at the center of the array.
In this embodiment the detectors are arranged in thin radially extending lines to permit accommodation to displays of different diameter. Alternatively, small detectors are arranged along a circle having a diameter which overlies at least a portion of the orbiting radiating element which radiates along a considerable length. This alternative array configuration also accommodates a range of display diameters. As a further alternative, to accommodate different diameter displays.
the thin line detectors may be replaced with radially extending light pipes with detectors at their ends. The transparent plate with almost invisible detection apparatus permits viewing of the depth sounder displey through the plate so that visual as well as audible readout may be achieved. Electronics is provided to decode the angular position of the orbiting element of the depth sounder at the time the element is actuated to provide a digital number repersenting depth. This number if then used in generating its speech equivalent through a standard speech synthesizer and loudspeaker. The electronics may include a number of different ROMS or different sections of a single ROM to provide for scale adjustment.
Alternatively, a variable rate clock may be used to adjust for scale. Alternative embodiments include sensing the time difference between pulses of electro-magnetic radiation from the depth sounder to establish depth, with the signals being available outside the depth sounder case. In each embodiment, signals which activate the speech synthesizer may be used to drive a digital display for improved filtering against spurious signals.

Description

FIELD OF INVENTION
.
~ his invention relates -to depth sounders and more par-ticularly to a method and apparatus for adaptiny a conventional analog depth sounder whlch displays depth in terms of -the presence of electromagnetic energy at a given anyle on the dis-play to give an audible indication of depth.
BACKGROUND OF T~IE INVENTION
There exist a number of analog depth sounders which provide a display of depth in terms of the angular position of a lighted neon bulb with respect to a zero, usually at the top of the display. These depth sounders in general incorpor-ate a neon bulb mounted on a rotary disk in which the neon bulb is actuated by the return of sonar signals which ha~e been pro-jected into the water and which are reflectecl either by the bottom of the ocean or by fish. The disk is driven by a syn-chronous motor which is timed in accordance with the transmis-sion of the signals from the transducer used with the depth sounder such that the angular position of the actuated neon bulb corresponds to the depth immediately underneath the vessel utilizing the depth sounder. A circumferential scale is con-ventionally provided on the display -to relate angle to sensed depth. As is conventional, the depth sounder is provided with an intensity control and the operator reduces the intensity of the neon bulb to the point at which only two lines are visible, namely the zero line and the first depth line. It will be appre-ciated that multiple lines can be viewed on the depth sounder display when multiple bounces of the sonar signal occur. By adjustment of the intensity level, it is possible to adjust the depth sounder such that only one unambiguous indication of depth is displayed.

~ t~

~3L7~
~ 'hile these depth sounders sre indeed gl~t ~ t~ nevig~t~on, espec~y in narrow ehannels, it is oftentimes inconven5ent to gl~ce et the GisplPy ~
try~ng to nav~gate in a crowded ch nnel. It will be ap~reci~ted that ~ ng at thedepth sounder to re~dout t~e depth is not on~y inconvenient, bl~t ~o ~n result in accidents due to glancing away frum the scene.
It is therefore desirable that ar audib~e indication o~ depth ~e pro~i~d ~o that khe operat~r of the vessel neea not divert his ~ttention from the s~u~tion ~t h&nd.
Moreover, s~nce depth sounders are freauently used in r~vigation, it ~s }ikew~e ~rable to provide sn audible ~epth in~ction ~or the ve~el's nz~g~
wh~se attention is ~rawn away from the chart he ~ ~g w~en he m~;t look ~ at ~he depth sounder in order to ascertain the oepth o~ the wster over whi~h the vessel is culTently pa~ing.

S~MMARY OF T~ L~V_~'T10~

In the s~abject invention a simple system fs pro~i~ed fo~ aoaps~g an ~la}og depth sounder such that ar audible indication o~ depth is pr~ded o~ Q reguler besLs, while at the sa~e time per~ftting the oep;h so:~er to p~oviae She no~m~l ~nsual display o~ depth. In one embodiment the ao~pt~on is a~'~ie~ b~ t~
p~acing o~ ~ transparent plate over the face o, bezel of t3~ th s~unc~er in ~hich the trarLsparent plste i5 proYided with e rsa~l~ runnin~ a-r~ 0~ pho~etecto~s.
The photooetector ~rray is arranged ~-~er the bezel su~ thet ~ o photooe~ect~r is located r~ llv et the same sn~le es the ze~o noteG on the ~e2el o~ the dept~7s~under. The array is made oi narr~ elements o- to ~-mit viewing o~ the c}ep~h sounder display through the plate and around the &~r y. Sin~e the photo~e~ector~~re ~rr~nged r~di~l~y, the plate can ~ccomm~ete v~i~u~ sizes o~ ~pth SC~30eI

~ 785~
displays ~r be~els since it is only nece~sæ y tO detect the an~lar oisp]scemen~
the neon bulb normally utilized.
ln an alterr~ative emb~dimen;, the ra~ array ol phDtooetector~ m~y t~e repleced with a radi~l arra~ of light pi?~s ~ith ?hotodetec~ors ~t .h~ ens~s ol the light pipes. In one emb~diment .the li~ht pipes m~y ~e fo~ med by radiPl~y r~ning score lines in the .transparent plPte. This con~igurati~n cont;ribu~es t~ the transparency of the array because the sco~e lines c~n ~e made exceedin~y~hin~
Thus, very little of t~e neorl bulb is obscured b- the opt5cal pick-off p~rtion of the sy~tem.
In ano~her emb~dime:nt, thP phot~detectors may be e.-r~nged Pbout t~e eircumference of the display ~ooking inwardLy to dete~t t~ radia'don ~rom tS~e ~d of the neon b~lb. ln thiis em~diment, the detector ~ay does not ~cclude the disp}ay ~t ~Lll so that normal visual reaoout is readily a~hieYed.
In a stDl further emb~iment ~ich does not re~uire light pipes, wnth sm~l detectors they may be mounted in ~ ring havin~ ~ a~amete~- which WOUlG overlie Pt least s~me po~tion ~ the neon bulb. Since the blllb emits rad;2tion over i~
considerable l~gth, ~uch an arr~y csn ac~omm~ate ~ ere2lt size di~le~, assuJTling the detector wiIl overlie at ~e~st e porSior~ c~f the bul~. Sin~e t~e dete~tors are small~ tl e disp)ay can still be rea~ through ~he ~ay.
The ~ar~sparency of the adsptati~n plate and the v~tu~ transpareD~y o~ ~
~rray permits adjustment of the inten5~ty eontrol for the aep~h SQUlldU' SlUC:h that only ~ne ~nam~igL ous irldicstion of depth is ~hieved. Th~s, the subje~ adaptation permi~ not on~y the audible i~dicP-ti3- Or depth! but ~lso d~ no; im~eoe ~isual reaoout o~ t?e oepth sounder by an in~vidu~10 ~ one emb~diment the ~utput of the dete~to~ ~rP~ is co~led to elet:~oni~s .and a speaker housed in a ur~it ~hich is .~OUnteG on top ol the ~onventi~n~l dep~h sbunder, whereas in ar ~Iternetive e~im~qt, the ele~onics ~nd ~æak~ &~e housed at the center of the array, with electrical power being applied, in one embodiment, by batteries contained within -the housing. In this embodiment, no electrical connections need be made either to the depth sounder or the ship's powe~ supply.
It is therefore an exceedingly simple matter to adapt the con-ventional dep-th sounder by merely placing a completely self-contained unit directly over the depth sounder display and turniny it on.
The electronics for reading out the array includes an array of threshold detectors, the outputs of which are lead to an angle decoder and depth code generator. It is the purpose of the angle decoder and depth code generator to sense which of the photodetectors is providing an output signal and to generate a corresponding depth code, e.g. a numbex equalling the sensed depth. The depth code is made compatible with the input code requirements for a standard speech synthesizer chip such as National Semiconductor Model DT1050. It is the function of the synthesizer chip to generate an audio signal coupled to a loud-speaker, which signal is the speech equivalent to the depth.
The synthesizer operates to generate the audio signal corres-ponding to the input code which exists at its input at the time a start signal is applied to the synthesizer.
In a preferred embodiment, timing is provided -to generate a start signal for the synthesizer unit such that an audible readout is achieved on a periodic basis. The timing unit provides a reset pulse to the angle decoder and depth decode generator either before or after readout as desired.
It will be appreciated that there need be no synchron-ization between the angle decoder and depth code generator and the depth sounder, simply because it is not critical to readout 78~
the depth at any particular instant of t.ime with respect to the actuation of the depth sounder.
However, in order to achieve multiplexing it may be desirable to provide a timing signal from the depkh sounder display, and this is simply accomplished by -5a-' . ~ L7~3S~
detecting the onset of the nash from the ne~n bul~ a~ the zer~ pos~tic~n ~f the depth sounder. ln this manner, the angle decoder 2nd de?th code ~en~.ator c2n ~e synchronized with the depth sounder opera~ion. This s-~chroniz~lion can established for the tirnirlg uni~ utilized to ~ctuate the syn~hesizer.
Sc~le ~djllstment ~or t~e ad~ptation unit may ~e ~chie~ed th~ough ~he utilization of a number of different read-onl~ memories (~0.!~1S) o; th~ utilization of differeslt sections o~ one ROM. Thus, the scale m~y be set b~ ac~uating ~
preselec~ed RON c~rresponding to, ~cr instance, depth r~es of ze.rC~ to flf~y fee~, zero to ~ty ~eet, zero to one hundreo feet, zero to one hunored ana tw~ty ~eet, etcetera.
ne em~t, the output of the ~etectcæ anay may ~ d~
uti~izing a coincid~e detector which is utilized to freez~ whi~ ~;
clock~ at a rate w~c~a corr~sponds to the peri~ci2y o~ the oep~l~ sounder ~spley.
This register is rcset by de~ded si~l correspon~ng to the ~h a~ the zer~
positi~n oI the depth sounder such thEt the register is increm~ed by~ tne elock . .._ til su~ 'dme as an output ~r~sn the ~oincioence detector Ireezes ;n~ re~s~er7 Note t~t a ~iable rate ~lock ma~ be utilized to ~eS tt~e r~ o~ t~ a~p~e;
modu~e t~ the rang~ of the depth s~under. ~ ?er~ion~ the re~er h~g ~e~
resct ~S æero, is ~l~ek~d ~t a pr~determined rate unt~l su~h ~me ~-a ~
t~te~ -T~hs fr~:2?:s the reg~ster. When frozen, the ~gister o~pu~ CO~pOYl~S
o the detect~r numb~, She ~gul8r po5ition of the &~S~tcd ~05~ ~g an~ thus the sensed depth 'rhe ~u~ut o~ the frozen regis;er may t~e~ be oecodecl ænd proi~ided to the. sforernentioned s-~nthesiz~ . The 5~ ntne~zer ~ tu~teci by E~
~un~e~duwn signal from the clo~k such th~t-the vutput o~ the ~log clep;h sounder ~s con-~erted on ~ periodic bqsis to the speech ea-av er~t o, ae~th It will be ~ppreciated th~t 2he neon bu~b norma3}~ useci geners~ ec~-~rnagnetie ra~iation not only in the v~sible region of the electsQn~egne;i~ spe~ m"

~L2~5~
but also at a wide variety o-E frequencies. Thus, the signal produces by the neon bulb actuation may be detected, for in-stance, by a capacitor array rather than a photodetector arra~.
Since the signal utilized to actuate the neon bulb is electro-magnetic in nature, an array of electromagnetic detectors may be substituted for the photodetectors. As such, this invention relates to the cletection of any electromagnetic radiation at an angle corresponding to depth.
As an alternative, any electromagnetic radiation pro-duced by the depth sounder in sending out or processing receivedsignals, which radiation is detectable without hardwired access to the interior of the depth sounder, is used to detect depth by the time difference between transmission and receipt of sonar signals. In one of these alternative embodiments, two detec-tors are used, one to detect electromagnetic radiation repre-senting a zero flash position, whereas the other detector detects electromagnetic radiation associated with all flashes.
In another of these embodiments, thresholding distinguishes between electromagnetic radiation representing a zero flash position and other flashes.
In each embodiment, signals used to dr ve the speech synthesizer may be used ~o drive a digital display. Because the digital display is actuated from the flashes as opposed to unfiltered electronic signals in -the depth sounder, the digital readout is extremely stable and accurate. This is because the depth sounder is visually adjusted to provide two and only two flashes. Thus, the optical link serves a filter function for removal of spurious signals.
According to one aspect, the present invention pro-vides apparatus for converting a depth sounder having an analog depkh indication in-to one in which depth is periodically called out comprising: means for sensing the analog depth indication;
means for converting the indication into a num~er; and means for converting the number into a speech equivalent.
More particularly, the invention provides apparatus for converting a depth sounder having a visual depth indication into one in which depth is periodically called out, said depth sounder having a case and producing pulses of electromagnetic radiation in providing said visual depth indication, the app-aratus comprising: means outside of said case for sensing the pulses of electromagnetic radiation; means for converting the sensed electromagnetic radiation into a number; and means for converting the number into a speech equivalent.
The depth sounder may include a display having at least one element which yenerates electromagnetic radiation at an angular position correspondiny to depth. In one embodi-ment, the adaptation takes place by locating a plate having an array of electromagnetic raaiation detectors thereon over the depth sounder display, with the array being arranged to sense the -7a-~ 2~ 85i~
angular p~siti~n ~t which the electromagnetic radi~2ion ~ generated. ;leans ere then provided ~or ~onverting the sensec position of th~ el~ctromsgne;ic r~niPtion into the speech equivalent o~ ~ number corr spondin~ to the depth repr~s n~ed by the an~ular posi~ion of the sensed radi2tion. For ~onve~ence7 ~h~ picte m~y be made transparent or ~lternatively, the ~rrsy mav ~e situP~ted so ~s nc~t t~
completely block the displ~y. Lr~ lternative embociament7 ~he tim~ ~ifference between p~Llses of ~Lash actuation radi~tion avPilP-ble outsioe the dep;h sounde.
case is used to convert depth ts the speech o~ di~itel eau~v~lent.

t BRIE~ DESCRIPTION OF THE DRA~T~S

Thesè and other featu;es o~ the subject inYention wi:ll be better ~n~eSood in cormection with ~ e~iled description taken in corljJmc~on With th~ w~gs of which:
Fig. 1 is ~ diRgrammatic and expl~oe~ ~ie- of ;~lr sub~ect ~dap~tion modu~e for utilization ~Yith a con~en~ionPl an~o~; de?th sounoer~ ~
Fig. 2 is B ~r~nt view of a con~æntionel anPlog oepth somde. ill~etrating the positioning o~ a transpsrent pl~te carr,~in~ a r&diall-~ ~xt~di~ arr~y o~ oe~e~tors~
ill~strsting the abiliSy.to ~iew the de?th so~oet nicpla~ '~o~ th~ dP~'~at~n m~dule; .:
. ~ig~ 3 ~s e diagr~mmatic illustretion of æbility ~ t~ s2~ec~ ~ptatio~
plate to accommodate dif~erent diameter dep;h soullQ~r ~:5pl~;
~ ~ig. 4 ~s a ~iagrammetic illust~ation and e~:plooed ~ie~ o~ ;he s-~je~;
adaptation module iJl~s~r~ting e self-~ont~'ned unit ~n w.~ch the ho~ing for ;he electr~nics and speak~ are l~c8ted Pt the center o- t~ ~--Ey on th~ picte;
~ig. S is a schemPtic diagrPm ~- one em~odi;~ent ~:~ s31e e~ectro~i~s u~llize~
to decQde the srra~ of Figs. 1- 4;

.. . .

( 3L;2~L78~L
Fig. 6 is a schem~ti~ dhgram of the angle decoder ~nd depth c~de genera40r ~or use in the cirulit og ~i~. 5;
~ ig. 7 is ~ s~hematic diagrRm of another type of angle decoder and d~pth code generat~r for use in the circuit of Fi~. 5;
~ ig. 8 is a d~rammatic represen-ation o~ an array usin~ radially rwLnir~
light pipes with p~otodetectors at the ends of the light p~pes;
Fig. 9 is a diagrammatic representation of a d~epch sounder with an ~dd~
unit which establishes dep~ 8S the time di~erence o~ r~diation emi~ed from the depth sounder;
Pig. 10 is a schematic di~ m of a sys~em for use ~n ~he urli~ of F~g. 9 in whieh the time dif~erence of radiation emitted from ~3e depth sounder is used to estabLtsh depffl for conversion into a speech eguivalen~;
Fig 11 is a schematic diagram of an alternatave ~rstem for establish2ng t~e time dif~erence o~ ~diation emitted fr~m the ~ep~ ~er o~ ~ig. 9.; and Pig. ï2 B a schematic diagram of a still further a}ternatlve system ~or determin~ng the time duration of an log indication dept~ signal~ aYail~ble outside of the dep~h sounder housing or casing~

BTI~II~D DI~SC~IION

In order $o p~vide a conventional depth sounder ~ith ~Ee ability to ~ e depth t4 the ope~tor of a vessel through the calllr~ ~t of a ~mm~r corres~3N~ing ts depth ~nd re~erring now to Fig. 1, a conventional dep~ s~nder 10 ~h~s a ~a~e or bezel 12 which has markings 14 correspondi~ to ~ depth ~c~e se~ ~ a se~le adjustment switch 16. Upon proper adjustme~lt of an ~ntensit~ con~ol 18~
two nashes 20 and 22 will oc~ur at the face of the d~iee between an inner c}rc~lar pla~e 24 ~d an outer plate 26 having fln aperture 28 ther through. ~e ~perture is ~ircular and ~i'ch the inner disk forms a ~hannel 3~ ~roug~ which the neon ~ulb proYiding ~ashes 20 and 22 is exposed~

t78531 As is convention~l in depth sounde.s ~ the æ~l&~ type, in~ensity ~ontrol 1B
may be aàjus~ed s~ as to pr~vide on}y ~ sin~le fl~sh 22, thereb~y eli~TIinati~g multiple representations of depth c~used b~ double bounce or ~rip3e bo~e situations.
~ s such, disk 249 plate ~6, circumlerenti~l ch~nel 30, ~nd indic~tis~ns of electrorD~gnetic ~nergy such as provi~ed by the rot&ting neon bulb, pro~de for an analog Cii5pl~1y oî t}~ depth of the ~ate. bene~th the vessel by v.irtue of tl~ ~ngul~r displacement o~ tll~ indicsti~n 22 ~rom the incicetion 20 ~hich e~rresponas ~ zero depth and ~ zero ~a~ the sy~tem.
ln gener~l, a sin~le neon bulb is mountea on a rotat ~le disk beneath ~he aforementio. ec display and ~ mounted to ~ s~rnchron~us motor ~not shc~wa) ~ nih synchroniz~s the actuati~n of the displR~ with the tr&n~i~te~ nnd received sonar P~.
In ~rder to ad~pt a st~dard de~2~.h so~oer o~ the ~ ]O~ t~e to pro~ide f~.
the call~ut of depth at regul~r in;er~PIs, her~inz~ter tef2r.ed t~ ~ "a te~icing depth sounde~ n ad~pter mooule 3, includes F trfinS?&~en~ plat~ 3~ ~ni~. is provided with a detector array 34 extending rec~ - p.edetermine~ angles so as to pro~vide, f~ ir~an~e, a resolution Or 7.2 co.responci;~ ~o one fo~ ineremen~
on a scale of 0 - 50 feet~ This tr~nsp2ren. 21~;e Prlc &~2~' is ar.~hed ove~ thE
d~splay/ in one emb~iment, bv pads 36 hP~in~ d~ e s~ick~ k ~pe Ynth ~
rcm~vable ~ver sheet. Array 34 is attached b~ cable 37 ~na ~nnecto~ ~8 to ~n electron nd speaker unit 40 which is couDlec to the ~æm~ power euppl~ as t~e ~epth ~o~mder. Vnit 40 has a speaicer 4~ ~ro~ ~hich an ~uGi31e ~a~ o~ the dep;h periodically emin~tes.
ln one emb~Qim2nt, ~rrPy 3~ includes ~ nurn~ c~ in~ividu1 snin lineal photo~etectors ha~ng e cornmor. inner contect 44 ~nd ~nQviduel out~- ~:ont~
and 48 coupled to c~nnector 38~ ri~ty indiviaual pnoto~etectors. ~.Tielc ~ on~ foo~

'G

~~z~

oepth resolution ~r depth sounders having P scale of ze~ to fif ty. C~
s?on~llgly, sixty photodetectors give a sne ~oot depth resolution fo' de?th sounde~s hsving a zero to si~rty scale~ Of course, half the number of photosetectors m~y utilized ~or hal the resolution.
Re~erring now ~o ~ig. 2; unit 10 with pla~e 32 in ?lace, an~icates ~ Lt because the plate is transparent end because the photode~ect~rs snay be m~de so thin that they can be see~ arDund, indications 2~ and 2~ ~re readily visibl2 through the adspter module. This has the &dvQntage o~ being ~ble to ~iew the displ~v ~n the normal manner, whereas an audible readout of dep-h is re~ o~tained oreover ~s illustrated in ~ig. 3, plaSe 32 w~th radi~ array 3~ ~he~eon, is ~daptable to displays of v~ying diameter. ~or instance, ~ lustr~ted at ~D, a necln bul~ orbited ~ Lnd in t~e arc illustrated vill lie adjacent sec~on ~" o~ ~ray ~4. A smptl~
display in which the neon bulb trevels around in the E~'~ desi~nated ~ se~erence character ~4, ma~ ~lso be ac~ommodated by the above PdPp;-ti~n te~nic~ue ~imply because o~ the recognition th&t the as~ r di~?lec~ n~ o~ de?;h ;.s the s2me regardless ~ the ~ameter o~ She ai~play. Thu5 the su~jec; Eoaptation moci~e arld techrLique may be utilized with an~log depth sounoel d~s~lP~ l~aVing` & W;de l~ariet~7 of di~ferer3t diameters.
R~erring n~w to Fig~ 4, in a further emb~imen~ the ~dapter modu}e ~ncludes a plate ~4 h~v~ng an arraS~ o~ phot~detecto.~ ~ t~ereon, ~h elec~
and speskE~r for the a~pter module being l~c~ted ~entr~y~ E~S illustr~ted a~ 58.
T~e advantag~ to this ~ut is thBt it is totell~ sel~-~or~a~ned ~ that housir~ ~78 can contain the batteries for 7l~owering the electronics. Mc~re~ve^, i; ~i~ p~reei-~teci th t tbe outer enas of the individu~l detect~ors o~ v are ~oineci a~ the periphery as illustrated at 6~ ~nd connecte~ to the elec1:~or~ics ~P li~e 6~
ConYenient~y, the inn~r end5 o~ the detectors m~v be eonnec~ed d;rect~y ~o the electronics in circuit board fashion, thereb~7 minimi~in~ the number o~ lesds which ~ ~7~
need be patterned onto the plate~ Unit 5~ is provided with an on/off volume control 64, a scale control 66, and a threshold setting control 68, the purpose of which will be clescribed hereinafter.
Referring now to Fig. 5, a plate 70 includes an array 72, with the inner ends being interconnected and connected via line 74 to one terminal of a threshold detector array 76 com-posed of individual conventional threshold detectors which are settable either individually or in gang fashion.
The other ends of the individual detectors in the array are coupled to the threshold detector array 76 such that each of the lines corresponding to a different one of the photodetectors is coupled to a different threshold detector with-in the threshold detector array. Thus, the number of lines to the threshold detector array is identical to the number of detectors in the array. The output of the threshold detector array is coupled to an angle decoder and depth code generator 7 which decodes on which of the lines from the threshold detector array a signal appears. This corresponds to the detection of an actuated neon bulb at a given angular position. The angle decoder portion of unit 78 determines which of the detectors in the array is generating an output and converts this number to a depth code which is supplied to a synthesizer 80 which converts the code into an audible representation of the depth. One such synthesizer is National Semiconductor Model DT1050. ~hen a code is presented to this synthesizer and a start pulse is provided, the unit generates an English language number corresponding to the input code. The output of unit 80 is coupled to a suitable loudspeaker 82 ~or the anunciation of depth. It will be appre-ciated that the synthesizer is provided with a timing unit 84 which reads ou-t unit 80 at selected time intervals. Power for the unit is supplied by a batter~v 86 contained within the unit.
As will be appreciated, an actuation signal may be provided b~
timiny unit 84 to readout the s~vnthesizer t.o the lo~l~speaker, Timing unit 84 also provides a reset signal to unit 78 to reset this unit either before or after readout ot s~nthesizer 80.

-12a-~ 2~ 35~
Should it be de~irable~ tl e an~e oecoGer ~ de~h generator unit may ~e provided with ~ synchronizfition sign~ ~rom th~ diS?l~y ot the oepth 50under E!Sin~icated by dotted errow 8B, which r~s ~rorn the ze,o p~si;ior, o~ ~he aisplay to the ~hreshold dnector array 76~ Th-~hold detector ~r,~y 76 p-oYides ~ si~ at the begirming o~ the zero nssh o;~ the display ~s oetected by the zero pho~odetector which signal is utilized either in unit 78 or timin~ it ~ to synchronize the operation of these ~its with ~he ope~;ion ~ the oepth sounde..
lt will hswever ~e ~ppreciatec th~; such timin5 is ~L~necess~-v since th2 subject ad~pter Tnodule merely conver-s en~l~r posi.ion o- ;he fl~sh to arl au~ible representation oI the depth represented by the fl~5h ~min~ is the.e~o;e not particul rly criti~l Imle~ multiple~ is desirable.
~ or ~nstance, ~iming unit 8~ mPy a~tuPte the ~nthes~z~ once every ~lve seconds, with She synthesizer reaGin, out tne output of u~ut 78 ~t ~lve se~snd interv ls. Since the glc~w of the ne~n bu!b is rel2t3~ ?~sisten;, a rel~ 7y constant ~utpu; is ?rovided ~hich can be dete~ted by ~~- th.e~ld ~te~to. end oec~ied by uni~ 78.
Referring to Fig. 6, in one e.~odimen; ~le de~o~er ~G oe~h ~ooe generator 78 inclooe; ~n angle de~oding ur~i; 9C, the c~u;~ut o~ ~7hich is c~elte~co-number ~orresponding ~o the oetectc~ which is ?r~qai~ an OUtp~lt ou~ to ~he ~ustion of a ne~n b~b at the angulPr posi.ion imme~iate~ eret~s~th. ~ne emb~dim~t o~ angle dec~de unit ~0 ~1 be oescribed in ~nnectic~n ~ . 7. In an~>ther embwiment9 the angle ~ec~oe un~t incluGee s~tc~e sample ~d holG
cireui~ and logic which recognize ;he prese~ce ~' si~EL fro~. p~eoe~e~ neo thre3h~1d oetect~rs and generate p.ecetermi~eG coa~3 reS?o~sive thereto. Th~e c~es iBentify the illuminate~ de;ector ~nd ~re ~oYi~et: ;o the depth cooe generator fot the generato~ of a s~nthesizer-comp~ti~le ~o~e. Timin~; lor the angle ~c~oe' m2y be pr~vided b! limin~ ~nit &~. ~QIe th~ ec~oer ~0 ma~

l ~ ~

.7~5~
be configured to muntain its sutput until s~1ch time P5 there is ~ chan~e o. iT~pU~.
As to the depth code~generator portio,l ol unit 78 encircled irl aotted bax ~2, fn one elr b~.iment ~his generator includes ~ series of read-o~.ly memo. ies (RO~as) S4 which convert the detector number to e code compatible v~i;h synthesiz~t 80 r ch ~OM or section o~ RO.M m~y be actuated by a ROh5 ena~e w~it 96 throu~h a c~e set swiîch 98 t~ actuate the particul.ar RO.'~q o. section of R0~5 correspDndis~g to the range to which the. depth sounder .s s~t.
It is the unction of the ROlt5 to p~o~ioe e lookup table fo, con.~;ing tho detector number-to a ~.tal c~de re?.~sentin~ the dep;h to t~e cF~i~d ou.. ~o.
instarcP, if the depth:is.~feet, the digtPl c~e 00~01ûU0 wol-ld be rea~out to . Model DTl050,-.. Nine:feet9~n the other h~nd, would re~ ~. a cooe o~ D00010û~
being read~ut:from the:~OMO ln fact in the above model ~nthesizer, e~des of 1 to 20 pr~ceed:in the usual binary ~shion.
It is.the .p~rpose.of timing unit 84 to provide 2 .eset p~ e ;o esch o~ the ROMs imme~ietel~ither before o. ~;er P re~oou~ puL~e is ~ e.~ tC s~n;h~
sizer ~0.
l~ ope..~tio~; angle ~ecoder 9~ provides ~ numbe~ Et its OUt2U; CO. . espcn~n~
to the il~umislated det~.cto.r. 'rhis number is m~intainec~ En~ ~ no; ~h~nge u.n}ess difîerent ~cts~ is illusr.inated. 'rhus, there is e~rlst2n; oetectc. numDe~ ~o ~e con~erted p~ri~ica31y -~y gener~tor 92. Gener~;or ~2 is pe,ioQ~cally rcse~, pre~era~ 2st ~ ore~~adout of the s~thesizer 80! s~ that ~ted in~ormPtion i~
reRd into Stle.s~mt-h~i~;r. As will ~e 5een, timin~ i5 no; ~ti~ nd the-e is n~
neeess.~ry. ~ynchroniz~ti~n with the de~; h so~\der .
:Referrmg-now to ~ig. 7, anrie de~ooin~ mPy be accom~ishe~ on a synch~
nous basis such that ~ ~ertsin amou~t o~ multipie~ng m2y ~e a~hieve~ througA the timing provided over~ e l00 from ~ 7~. In Fi~. 7, the C~UtpU~ oi the 8~By is pro~n~ed to t~reshold detecto. 1~2, ~hich i then ~upled to ~ eoinciden~

.

detector 10~ which provides a freeze pulse over line 106 at any time that an individual detector of the array has an output associated therewith. The output of the freeze pulse is applied to a register 108 which is clocked by a clock 110. ~egister 108 is reset via a signal delivered over line 112, which is generated by a threshold detector 114 coupled to the zero photodetector element of array 72. The output o register 108 is decoded at 92, the output of which is applied to synthesizer 80.
Clock 110 is a variable rate clock which may be adjusted to the scale of the depth sounder. Synthesizer 80 is actuated by a counted-down signal from clock 110 provided by count down unit 120.
In operation, when the neon bulb reaches the zero angle, the output from this detector is detected at 114 which resets register 108. Thereafter, during the cycle of the depth sounder in which the bulb rotates 360~ back to its original position, register 108 is clocked at a predetermined rate. If, during this cycle any one of the individual detectors of the detector array provides an output signal, it is detected by coincidence detector 104, which freezes register 108 at the particular number it has been counted up to. This number cor-responds to the angle at which the flash from the neon bulb occurred, which in turn corresponds to a predetermined depth.
The frozen register is readout to a decode unit 109 which con-verts the register count to a number code acceptable to syn-thesizer 80. Alternatively, if the output of the register is a binary number representing the register count, the register can be directly read into the synthesizer. It will be appre-ciated that angle decode unit 90 recycles once every revolution ~ 2~8~i~
of the disk carrying the neon bulb, the decoded output of reyister 108 being utilized to actuate synthesizer 80 in timed relationship to the synchronization provided by the dlsplay.
Clock 110 is a variable rate clock which may be adjusted conventionally such that the number called out matches the depth which can be visually -15a-:

~scertained by looldn~ at the displP~. ln other ~or~s, clock ilO ~reou~nc~r mey b~
adjusted until the armounced depth ~na;ches thPt which is readPble on the displ~v Thus, there need be no pretuning oS the clock to tne particul~r 4ep~h soundPr.
Note also that in fhis emb~diment, rnultiple RO;~s rl~ed n~t be u~sed ~or sc21 Adjustm ~t.
Wh~t h~s there~ore been provided ~s 8n adapte~ m~e ~h~ch ~dapts ~ny .
analog depth s~under to be a t81king device in whi~h depfh as c~31ed ouf on ~
regular periodic b~sis. Synchronization need not be p:o~noed, o~ i~ it is p~ovided"s provided very simply without sccess to ;he ih;erior ~ the cieptn s~2:nde.- or i~s electronics.
ln o~io~, the adapter and module may merel~P be p~eà ~v~r the fia~ O~
the depth s~under, turned on, and simply adjusted by llrst adj~t~ the inter~ty l~ob of the depth sounder to p. ovide only one n~ze~o indicati~;~ o~ dep-~L
Thereafter, the sca~e oi the ~d2pter ;nodule is eithe~- s~ o. experi~nen;~ . founG.
Dependin~ on the neon bulb utilizec, ;he ;h-es~ol~ ~rcui~ ~; ~e s~; in ~,~g fPehion or adjusted in~ividu~lly. ~;oreover, aoP?tive th-esh~aing mEy be p.
to adapt îo~ ambient light conditions.
Referrin~ now to ~ig. 8, in o.der to reduce the exDens~ in ~3~e m~ cture of the detector ~a~? it is possible to provioe tran~aren~ plate 32 ~i~h radia~y e~tending lig~t pipes, with the light pipes lead to an ~ray o~ e~ is ~e purpoee o~ th~s cmb~iim~nt to limit the size of the oetect~ nd ~here~r~re the overall ~ost of the ~nfiguration. As illus;r~ted m Fi~. ~, light pipes 1~0 rl}n radi~lly ~5 ~d t~e phot~detector~ in ;he ?re~qo~5 eh~d~men~s. ~etec~ors 1~2 Q'~
m3unted at one e~d ffr the other oS ;he co.res?ondi~ ight pipes, wiSh the outpuss of the detectors being ~upled Yi connecto- 3~ eno ~able 3- to the ~ppropri&~e pr~ce~ing cireuitry. As s~ch, the li~ht pipes ~nd th~ Detectors Io. m ~e ~

L71~3S~L

One way o~ ~orming light pipes in an in~xpensiY~ ~nner is lo sc~re t~e tr~s~sp~rent pl~te or etch it in such e ~ n thPt li~h; occur.ing ~ong B ~iven radial line is ~ransmitted from the poin; o~ intercep; to t~2e end o~ t~ line 7~a ~h~
columnation provided by the light pipe strueture. Since deteclors c~n be m~unte~
at the periphery of the display either line~rly or alon~ a eircum~erence7 ~he spacing betwe~ the dete~t~rs is not particulerly criticP!. Adciition~ly, extre~ely sm~ll photodetectors may be utilized due to the rether l~r~e m gr~itude sign~l prt~vid~d by the neon bulb. As il~ustrated, the detectors are located ~-oun~ th~ cir~u.nfe.--ence of the array. Altern~tively, Decause the detecto.s rrl2V 3e m~e excee~ngiv small~ they may be mounted at the interior enQs o~ the li~t p~pes ~r~m whence "Lhe ~utpu~ may be ~nneeted directly to a printed circuit board cE~-ried at the cerl~er c~f pl~te 32, It will be ~ppreciated thQt t~e utilization o~ s~r~e lines for }ight pi?es o~
light p~pes themse~ves permits the vie~ing of the depth 50Un~e'.' displ2~,- ;hrou~h the transparent plate. Moreover9 the scri~e lines cEn ~e m~e ~x~eeQing~ ;hi?.. bo;h improving resoiution and decreasin~ cross-t~lk between li~ht ~i~. ~e.n~c~ll.9 light pipes or o~l~r light ~hannelin~ s;ructure~ can ~e fc~me~ either on o. irl ~he transparent plate w~th ~uitabh cl~ddin~ or coPtings to pr~ven~ ~ros~;~ ~ote tha~ ~y suitable slanted end~lice ~onfigurations, li~ht ~;~ ;he neon bs~lb can be made to enter the light pipe ~rom e rsn~e of p~sitions el~ t~e length o~ ~he pipe.
A~tern~ dy, the light pipe can be flattened on the tmd~e~;~ ~de tc~ sdmit ~igh~.
Ad~i'tionally, it will be appreciated that the detec-ors m~ oate~ ~ith ~ red traRsmissive m~terial to elimin~te the e~çcts OT sunli~ imp3D~in~ on ~he moci~}le.
Sin~ the ~etectors can be maoe exceedingly small, thev wou~d not blo~k much light - from the neon bulb, ~v~c since ;he bul~ em~ts raaiP~ao~ ~ver Q
consider~le length, ~ight pipes neeo not be use~ ther. ~s illustrated7 P
detector 1~4 m~y be mounted ~n~ ~ !edilL; ii6 at ~ poir.t rr~id~y ~lo~g bul~

\~ ~

, .
. .

8~

envelope 158. The locus of the detectors defines a circle 160 which overlies a-t least a portion of the bulb for a range of display diameters. The result is that a ring of detector~ at a given distance from the center of the display would accommo-date different diameter displays assuming at least a portion of the bulb underlies the detector.
If desirable, for all embodiments adaptive threshold-ing circuitry may be provided to adjust the thresholds of the threshold detectors coupled to the outputs of the detectors so that the depth sounder may be utilized in bright sunlight.
While in the aforementioned embodiments the angular position of the flashes of an analog depth sounder are ascer-tained, the analog depth sounder also produces radiation which triggers the neon bulb utilized in giving the analog indication of depth, which radiation is available outside the case of the depth sounder. The electrornagnetic radiation responsible for the zero flash indicates the time at which the sonar signal is first initiated, and the electromagnetic radiation utilized in generating the second flash establishes the time at which the reflected sonar signal returns. By utilizing a receiver which detects such electromagnetic radiation outside the case of the depth sounder, no access need be had to the interior of the depth sounder. At the same time, this radiation establishes a time difference which corresponds to depth. In one en~odiment, the electromagnetic radiation sensed is the 200 KHz signal which is utilized in driving the sonar transducer, whereas in another embodiment, either the high GHz radiation resulting from firing the flashlamp or the flashlamp emission itself is utilized to develop the required timing signals which are then converted into depth and subsequently into the speech equivalent by a speech synthesizer.

. .

s~
One of the dif-Eiculties in establishing depth by this method is es-tablishing the identity of the electromagnetic radiation representing zero depth as opposed to the electro-magnetic radiation representiny the return sonar signal. As will be descrihed in connection with Figs. 9 and 10, the electromagnetic radiation representing the zero flash is estab-lished by a photodetector placed at the zero position on the face or bezel of the depth sounder. This photodetector detects only the zero position flash. Electromagnetic radiation repre-senting the second flash is detected either by an RF detector or by a photocell which can view the entire face of the depth sounder. The output of the zero position photodetector unam-biguousl~ detects the zero flash, with the length of time between it and the second flash establishing the depth.
In another embodiment, the intensity of the originally transmitted signal is usually hlgher than the intensity of the return signal and thresholding circuits are utilized so as to establish the signal with the largest magnitude as the one indicative of the electromagnetic radiation representing the zero position.
Referring now to Figs. g and 10, a flashing or analog depth sounder 170 is provided which in general provides two flashes of light 172 and 174 on its display. An add-on unit 176 provided with a digital depth indicator 178 and a receiver 180 is mounted on top of depth sounder 170. This unit provides both a digital indication of the depth subsequently decoded and its speech equivalent. A photodetector 184 coupled to an amplifier 185 and a squaring circuit 185 is placed over the zero position so as to produce a pulse 187 when a flash occurs at the zero position. Receiver 180 also produces a pulse 188 ~ ~7~5~
from the electromagnetic radiation assoclated with the zero position flash. It is a feature of receiver 180 that it pro duces a pulse when the depth sounder is actuated to produ~e a flash at any position.
A time thereafter, a pulse 190 is produced by receiver 180, with the time difference between pulses 186 and 190 beiny used to establish a depth e~uivalent. In one embodiment this is accomplished through the utilization of a coun-ter 192 clocked by a variable rate clock 194, with counter 192 having reset and freeze inputs as illustrated. The output from squar-ing circuit 186 is applied to reset counter 192 in a periodic basis as described hereinbefore, whereas pulses on line 196 from receiver 180 are coupled to an AND gate 198, which is in turn coupled to the freeze input of counter 192. The outputs of squaring circuit 186 and receiver 180 are coupled to an AND
gate 200, the output of which is inverted at 202 and is pro-vided to the other input terminal of AND gate 198.
The output of counter 192 is coupled to a decode circuit 204 which is utilized to drive a speech synthesizer 206 which drives a loudspeaker 208. The output of decode unlt 204 is also utilized to drive digital display 178.
In operation, photodetector 184 produces pulse 186 which is utilized to reset counter 192. The output of this photodetector is ANDed with the output of receiver 180, with the result that the simultaneous occurrence of pulses 186 and 188 inhibit the freezing of counter 192 which would ordinarily have been frozen both b~v pulses 188 and 190. Thus, only pulse 190 freezes counter 192. It will be noted that an output of a variable rate clock 194 is applied to a divide-by-N clr-cuit 210 which is utilized to read out decode unit 204 to the speech synthesizer and the digital display on a periodic basis.

L7~
It wlll also be appreciated that an intensity con-trol 212 may be utilized to adjus-t the outpu-t of the depth sounder to produce two and only two flashes. This in and of itself provides a filter :Eunction such that the digital display and the speech synthesizer are not actuated by double bounce or triple bounce spurious signals. The utllization of the visually adjusted ~lash or flash actuation signal reduces spurious signaL activation of the talking depth sounder by virtue o:E the adjustment of the intensity control to produce two and only two flashes. This solves a significant problem with respect to other types of digital depth sounders in which no such visually actuatable filter system is provided.
While the system described thus far utilizes a photo-detector at the zero position to provide an unambiguous zero position signal, as illustrated at the top of Fig. 10, thresh-olding circuits 220 and 222 actuated by switch 223 may be utilized to dlstinguish the electromagnetic signal representing the zero position from the electromagnetic signal representing the return signal. These signals may be utilized as above to reset and freeze counter 192, with the signals also being provided to AND gate 200 to inhibit the freeze. Thus, the circuit at the top of this figure may be utilized to drive coun-ter 192, decode unit 204, speech synthesizer 206, and digital display 182 in the manner described in connection with the system utilizing the photodetector at the zero position.
For those instances in which it is inconvenient to identify the zero flash, the system of ~lig. 11 provides for determining the time differences between the flashes without identifying the zero flash pulse. This sys-tem does, however, require the user to selec-t whether the unit is to sense flashes ~L7~S~
from 0 - 180 or from 180 - 360 because the system cannot distinguish between time intervals associated with the two different segments of the display. This system does not re-quire thresholding circuits to determine which pulse corres-ponds to the ~ero position flash, but rather leaves it to the operator of the device to switch between one of two ranges.
If the user s-~itches so as to choose the shortest of the two ti~Le intervals, this correspon~s to depth as repre-sented on the depth sounder as being between 0 and 180. Choos-ing the shorter time interval -therefore may correspond to a selection of between 0 and 25 feet. On the other hand, selec-ting the longer time difference results in a depth indication of between 25 feet and 50 feet in the foregoing example. It will thus be appreciated that the longer time interval corres-ponds to the time it takes for the rotary element to revolve from zero position past the 180 position to a position between 180 and 360. The selection of range can be easily ascertained by visual inspection of the depth sounder so that the appropriate ranges selected. Again, the range of the add-on unit may be adjusted to the range of the depth sounder by virtue of a variable rate clock.
In the illustrated embodiment, in order to accumulate time differences relating to the lower scale or the higher scale, receiver 180 is coupled to a JK flip-flop 232 which triggers on the negative going portion 234 of a pulse from receiver 180. The Q output of JK flip-flop 232 is coupled to a counter 236 -to enable the counter whereas the Q output of JK
flip-flop 232 is coupled to counter 238 to enable this counter.
A variable rate clock 1~4 is coupled to the clocking inputs of these counters. The output of receiver 180 is also coupled to the input of a monostable multivibrator 240 which triggers on the rising portion 235 of the pulse from receiver 180. This produces an elongated output pulse 242 which is coupled to one inpu-t of NAND gates 244 and 246. The output of NAND gate 244 is coupled to the reset terminal of counter 236, whereas the output of N~ND gate 246 is coupled to the rese-t terminal o~
counter 238. The other input to NAND gate 244 is col1pled to the Q output of flip-flop 232, whereas the other input to NAND
gate 246 is coupled to the Q output of flip-flop 232. The outputs of counter 236 and 238 are respectively coupled to memories 250 and 252 in logic 254 which functions to select either whether the count in memory 250 is larger than the count in memory 252, or visa-versa. This choice represents the afore-mentioned range selection. Memory loading is accomplished via the connection to the Q output of flip-flop 232 such that the memor~ associated with one counter is loaded when the other counter is counting.
In operation, upon the receipt of the first pulse from receiver 180, the positive going portion resets counter 235 since at this point the Q output of flip-flop 232 is high.
On the trailing edge of this ~irst pulse, ~K flip-flop changes state so as to enable counter 236. Counter 236 continues counting until it is reset by the second pulse from receiver 180 in response to the resulting pulse 242 from monostable multivibrator 240 and a change in the state of flip-flop 232 in which the Q output goes high.
When the Q output of flip-flop 232 goes high on the negative going edge of the second pulse, counter 238 is enabled, this counter having been reset on the positive going portion of the second pulse by virtue of the output of the multivibrator ~78S~
being dellvered to NAND gate 246, along with the previous pulse-high Q output of flip~flop 232. Counter 238 continues to count until a third pulse is received from receiver 234 which changes the state of the Q output of flip-flop 232 and therefore disables the counter 238.
Counter 236 is readout to memory 250 when Q is hiyh and counter 238 begins its count, whereas an inverted signal from the Q output via inverter 256 is utilized in -the loading of memory 252 when counter 236 begins its count.
It wi]l thus be seen that the outputs of the counters correspond respectively to two time difference intervals since during a given cycle, the counters will accumulate different counts. These counts are read into the memory of logic 254 which selects on a periodic basis the contents of memory 250 or the contents of memor~ 252. If the shorter time interval is desired for flashes between 0 and 180, circuits within logic 254 determine which of the two counters has the lowest count by determining which of the two memories has the lowest count.
This output is then supplied to decode unit 260 which decodes the number and supplies signals to either speech synthesizer 262 or digit21 readout 264. If, on the other hand, it is desired to readout the range from 180-360, the memory containing the larger count is read out to decode unit 260.
The comparisons and readout of logic 254 and decode unit 260 is, as described before, under -the control of clock 174, the output of which is provided to a divide~by-N unit 266, having its output coupled to logic 254 and to decode -23a-~ L7~
unit 260. rrhus at ~ny given time selected for readout, either memory 250 or memory 252 will be readout go deco~e unit 26Q.
It will be ~pprecisted that receiYed 180 may be adapted to detect radi~tion ~t any r~isn in the electromagnetic speetlrum ~o as to produce outp~7t pulse~
correspondirlg to ~ash ~ctuation sigr~ls or the ~lash itsel~. In so doing~ U~
provided ~top the depth sounder need not be directly connected to ~y el~troni.
circllits of the depth sounder, but rather may include detect~rs which detect electrom~netic radiation avaîlable outside the case of the depth sounder_ Referring to Pig- 12, it msy be desirable to re~eive ana}~g depth indication si~ pr~duced by the depth sounder by tapping of~ the cable to the ~ansdu~er) thereby to e~iminate the necessity of identi~ing the zero si~nal by virtue of a photodetectGr. It has been found that the tappi~g off of 8 sigTl direct~ f~om ~e cable from the depth sounder to the tra~sducer p~vides ~n exception~lly "~at" s~l which may be utilized to provide ~or the ~nnuncsation ofdepth and which csn be utili~ed whether or not the dep~ under is an analog - depth` sounder or a digitai depth sounder. Ir this s~stem a depth sounder 300 is util~zed to p~oduce ~coustic signals which are transmiUed ~hrough ~ ~-~e adapter banana pl?lg 31D to Q ~able 312, with a portion of the signal a~rail~ble be~
tapp~d through the nT" cor~ tion 314 and through an optional ~solQtion ~r~it 31&to 8 pair of dete~tors 318 and 3~0, which in one em~odiment can be one ~et2ctor witl~ a ~road bandwidth response. The outputs of detect~rs 3~8 and 320, which ~noptio~a~y be ~lltePed, ~re respectively coupled to compsrators 322 and 32~ with the vutput of comparator 322 being coupled to a ref~ce v~ltage V
comparator p~oduces ~ pulse 324 whi~h is delivered ~ the reset terminal o~ ~
counter 326. The ~utput pulse 325 o~ threshhold dete~e)r 3~ ~s coupled to the freeze terminal of counter 326 ~nd also ~ia an ampl~fie~ 328 to an indic~tor 33û tQ
: indicate that return signals are in fact being dete~ted by the s~ject circui~

~.7~
Tne output of counter 326 is coupled to an optional decode cir~uit 332 which converts the output o~ the counter into a c~ing s~stem suitable for speech syn~esizer 334. The output of speech SyT thesizer 334 is coupled via an amplifier 336 to a vo~ume control on/off circuit 338 which cc~uples the output of amplifi~ 336 to a suitable loud speaker 340. The on/o~f switch 344 p~r~ion of cir~uit 338 is coupled to the potentiometer 342 portion of this ~rcuit, Ihe oup~t of the speech sy~thesizer as indicated may be coupled to an LCD display 348 which has an internal latchir~ ~ircui~¢y to }atch the last provided number until ~;uch ~ime as ~here is a refresh update from the speech synthesizer. The ~utput o~ the speech synthesizer is dumped by a pulse from a divide~y~ uit 350 which may be variable and ~nclude a eounter wit~2 a number of taps snd a switch to co~nect a desired tap to the synthesizer to provide a desired repetition r~te of the an~unciation. A~so, the snnunciation rate may be a~tQmatic~ incre~d with decreRsing depth.
In one m~destl~riced embodiment9 the decode ~cuit and speec~ ~ynth~
sizer circuit oRly synthesizes numbers from 1 to ~0, the-e~ to provide safet~7 in sha~ow w~ters for most s~esse3s. Should the depth exceed the ~iepth capabi~ity of the Ulli~7 the operati~n of the cir~uit is sti~l ascert2ir3ed by i~dlcator 330 ~ ~t even though there is rlo verbal annun~i~tion, the indic~r indicates that the ~em~s operat~ve ~t least insofar as it is receiving and dete~t~ ~ned s~a}s ~ eshhold circuit 324 may opti~nal~y be.provided wih a gain ~on~ol m the form og resistor 352 although this may be preset ~t the fR~to~. I~ will be a~ted~t ~he thres~old d~t~ctor 324 is supplied with a vol~ge V2 whi~h ma~ be all th~t is ne~essary, since the magnitude og the outgoi~ 5i~aI e3ceeeds b~ an or~er oî
magnitude thst whi~h is received.
lt will als~ be ~pprecidted th~t a feature of the wbje~t ~ventior~ he ~ounter 326 wi3} reeze upon any output from threshhold dete~tor 324 so th~, as a (( C ~ 2~
safety ~eature, even fish s~tting of~ the circuit will not present a problem. ~he reason is that the annunciated depth can be compared with the depth sounder indicatior~ to i~dicate whether it is a ~ue bottom read~D~ or ~t produ~d by ~h Double bounce is not a problem with this circuit sin~:e any subs~uent ~log indications of dep~ will be ignored becau~e counter 326 h~s been ~oze~L
It is considered that the analog signals along csb~e 312 c~n b~ ~app~d outs~de of the àep~ sounder housing Qnd therefsre constitute an analog depth i~dications available ~utside the casing.
In operation, one rnethod of the utilization of the c~uit o~ ~. 12 ~or a given depth is to adjust the gain from zero until spee~h is first heard. I'he speech e~uivalent is then che~ked against the indication from the depth sounder to see whether or not i~ is a true or false resding. If too maT~? unwanted false re~dings occurj th~ g~in is reduced until the Yoice-indicated dep~ uiva~ent to that indicated by the depth sounder. lf the subject unit a~iates z~ro, or ~here is no sound, ~en ffle gain is increased until such time as the appropriate depth is annunciated. Ihis procedure should be used for t~le ma~cimum depth desired to be measured to assure operation at all lesser depths. i~
As mentioned above, since Y1 is very much greater th~ V2, th~ sub3ect unit~ in it~ least eaq?ensive emb~diment~ may be presdi~ed at the ~actory and may . .
be limited in depth to, for instan~e, 20 feet. Outputs of counter 32~ indicaS~ve of d~pths over 20 feet would not be decoded and there~ore ~ere would be no ~put from the spee~h synthes~zer 334. Elowever, indicator 330 ~ou3d in~i~te: the operation o~ the unit insofar that it indicates the de~tion o~ re~rned signals, go th~t operator would know that, while he is in deepe~ læater tl~ the 2û-foot z~age limit of the unit, the detect~r portion of the system is in fact worku~g ~nd thBt when the veæel re~ches the 20-f~ot limit, speech wi~ begin.

' Lt78~L

It can therefore be seen th~t the subiect circuit may be uti~ized with ~ny type of depth souDder which produces acoustic sign~2C to be transmitted ~ia cable to a transducer and which in turn receives renected s~g~ls YiE~ the sarne cable.Having above indicated a preferred embodiment o~ the pr~ent invention, it will ~c~ur to those skilled in.~h& ~t that m~difications and alternstiYes can bepracti~ed within the spirit of the invention. It is accordin~ly intended to define thè
scope of the invention only as indicated in the following claims.

,_ ...

~ . . .

Claims (8)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. Apparatus for converting a depth sounder having a visual depth indication into one in which depth is periodically called out, said depth sounder having a case and producing pul-ses of electromagnetic radiation in providing said visual depth indication, the apparatus comprising: means outside of said case for sensing the pulses of electromagnetic radiation; means for converting the sensed electromagnetic radiation into a number; and means for converting the number into a speech equiv-alent.

2. The apparatus of claim 1 wherein said depth sounder includes a display having an element which is driven to provide a depth indication, wherein said sensing means includes means for sensing pulses of electromagnetic radiation associated with driving said element, and wherein said converting means includes means for ascertaining the time difference between said sensed pulses.

3. The apparatus of claim 2 wherein said element is dri-ven once at a zero depth indication and once at a time there-after corresponding to sensed depth and wherein said time dif-ference ascertaining means includes means for unambiguously sensing the pulse of electromagnetic radiation associated with said zero depth indication, means for sensing the pulses of electromagnetic radiation associated with all depth indications, a counter, means for starting said counter responsive to a sensed pulse of electromagnetic radiation corresponding to said zero depth indication and means for stopping said counter res-ponsive to a subsequently sensed pulse of electromagnetic rad-iation corresponding to any depth indication.

4. The apparatus of claim 3 wherein said unambiguous sensing means includes means at the zero depth indication position of said depth sounder for sensing the output of said element only at said zero position.

The apparatus of claim 3 wherein said unambiguous sensing means includes means for sening all of the electromagnetic radiation associated with a depth indication, and threshhold means for establishing the strongest electromagnetic radiation by producing a signal responsive to the sensed electromagnetic radiation exceeding a predetermined value.

6. The apparatus of claim 2 wherein said sensing means includes means for generating output pulses corresponding to all of said pulses of electromagnetic radiation and wherein said converting means includes means for ascertaining the time differences between successive pairs of output pulses thereby to establish two time intervals, and means for selecting either the greater or smaller time interval as that which is converted to a number by said converting means.

7. The apparatus of claim 1 wherein said depth sounder has an acoustic transducer and a cable connected between said transducer and said case and wherein the sensed electromagnetic radiation is that transmitted through said cable.

8. Apparatus for converting a depth sounder having an analog depth indication into one in which depth is periodically called out comprising:
means for sensing the analog depth indication;
means for converting the indication into a number; and means for converting the number into a speech equivaltent.