CA2095283A1 - Method for producing an interference-free radio connection - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

In a method for channel scanning by the receiver of a teleaction system, the squelch signal of the HF part of the receiver is scanned for the presence of an HF signal on the tuned-in channel, and only after that, depending on the outcome of this scanning, are further switching or evaluation processes of the receiver initiated. As a result, the channel search conventionally employed is speeded up substantially by scanning the received telegram addresses without requiring additional effort or expense, since the squelch signal is already available in any case in the conventionally used standard components from which HF receivers are assembled.

Description

2~5283 PATENT

ME~QD FOR PRODUCIN~ ~N IN~RFE~NOE-~R~
RADIO CONNECTION

BACKGROUN~ O~ TH~ INV~NTION
~ he ln~ention relates ~o ~ metho~ ~or establi~hlng an lnterfQrenae-~ree r~dio aonnection between tran~mittlng means ~or transmitting hlgh ~r~quency ~ignal~ at a plurality oP radlo Pre~uencle~ and a recelver tunable to eAoh one of the xadio Proquencie~.
Tho tran~mi~sion oS contro} informAtlon in remo~
oontrol, or teleAa~ion, ~ystem~ ha~ hee~ known ~or a long tlme ln prlnclple Por lnstance, German Patent No. 3~ 13 10 ~Z0 di~olo~e~ auah ~ 8y8tem Por transmltting control oommand~ by mean~ o~ an H~ ~ran~celver ~y~tem. ;~
For transmitting the command~ ~D-¢alled ~telegr4m~', or aontrol mos~Agos, ~re used, whioh aon~flin no~ only the ~tual ~ontrol aomm~nd~ Por the machlne to be aontrolled ~Ut ~l~o A unlque code, or ~ddre~, ~equenae identl~ylng a par~icular reaelver. By evaluAting this addre~e eoquonce, the reGelver ~n asoertaln whethor th~ ~elogram~ are ~rrlvlng frol~ the tran~mltter aseigrled to lt or not. The~e ~elegrAm~ are generated ln the remote aontrol transmltter by a aorresponding electronla clrcult (enaoder) and modul~e ~he HF ~rrier ~ignAl gener~te~ by the HF tran~mitter.
Typically, this is a frequ~nay modulatlon. The reaeiver receive~ thie modulated HF ~ignal with the aid o~ an HF
receiver part tun~d to the HF aarrier~ which in turn, after demodulation, outpUts the or~inal telegrAm to ~he decoder unl~ or uni~ which then ~urnl~h the de~lred control slgnal Por the maahine to be ~riggered. The appliaable prlnciple here is that the control ~ommand~
are allowed ~o ~e pa~ed on ~o ~he ma~hln~ only iP the addre~ in~ormation xecovered ~rom the ~elegram ma~he~
~he addre~ informatlon permanently programmed in ~he remote control recel~ex.

209a283 PATENT

A6 in the a~orementlonod German Pa~en~ ~o. 3B 13 820, ~or example, eaoh of the H~ ~hannela ~o whiah ~he reoeiver aan be tuned must be examlned for whcther the h~ ned tran~mltter le transmltting or not J thi~ mean~
that the recelver must ~1WAY~ wait Por tho r~pon~e ~om the teleg~am decoder bePore it aan chea~ ~he next ahannel ln a ahannel oearoh. Thl~ typlaally tako~ ~ul~e a ~ong tlme, beaauae only a~ter a certain period o~ time aan 1~
be a~umed that the negative re~ponse o~ the telegram decoder is due to the fAot that either no tnlegram, or a teleg~Am foreign to the 6y6tem, ha~ been reçelved.
~ his takeo a relatlv~ly long ~im~, ~o that a~ter A
frequenay ahange on the part o~ the tran~m~t~er, A
oertain period of tlmn pn~e~ until the receiver, by 15 meAn8 0~ the a~orementloned prooedure~, has ~oun~ ~its~
channel onçe again and oan loçk Oh~O 1~.

~VMM~RY OF THE INVE~IO~
The ob~eo~ o ~he lnvention 1~ to improve the ao pxeviou~ly ~n~wn ~ethod ln ~uch ~ way a~ to speed up the channel ~earoh proce~oe~ by the receiver.
According to the invention, thle ob~eot i~ attained, ~n a method for ea~abll~hlng an inte~eren~e-~ree rAdlo ¢onheotion between transmlttin~ mean~ Por tran~mi~ln~
high ~requenay signal~ at a plurallty o~ radlo ~requenaies and a recelver tunable to eaoh one oP the radio frequenaie~, w~iah method inalude~: tran~mltting, ~rom the tran6mitting mean~, control message6 ~t at lea~t one of ~he radio ~rcquenc$e~, each aontrol me~age includlhg an addre~s ~equence speciPic to the receiver~
turnlng ~he receiver t~ one of the radio ~reyuenoie~; ~nd determinlng whether the sign~l at the xadlo ~requency to whl~h the receiver i~ tuned oontain~ the address ~equence ~pecifia to the receiver, by the lmprovement compri~lng:
derlving, ln the recelver, a ~quelch ~lgnal having a ~ir~t slgnal statR when a hlgh ~equency ~gnal l~
preeent at the xadle ~req~ency to which the receive~ ls tuned, and a second ~l~nal ~tate when a hlgh ~requency ~ignal i~ not pre~eht At the radio frequenay to whlch the receiver i~ tuned: ahd ret~n~ng the receiver to another 2~283 PATEN~

one of the radlo f~equencle~ in re~pon~e to a ~eleated elgnal ~tate o~ the ~quelch ~lgnal.
~ he ~undamental concept o~ the inventlon i~ that the ~uelah signal, whlch i~ typioally available ln the ~tan~ard ComponentB ~rom whioh HF reael~er~ are a~em~led, i~ evaluated aa ~a~t ln~ormatlon ~or initlating further ~witahing p~ooes~e~. It 1~ a~umed then that the sq~elah si~nal a~t~ as g~ne~alized l'bu~y informati~n" on the HF ch~nnel ~u~t then tuned ln by the recelver; that 1~, lt ~urnlshe~ ~he ln~ormation a~ to whether thl~ channel l~ bu~y at all, or not. For many mode~ of operatioh and swltGhlng pro~e~e~ thl~
lnformation iB initially entirely adequate for in~tlating the nexS ~tep in the method, becau~e ror instance 1~ ~he ~quelah glgn~l indicate~ that the ~hannel is not at all oooupied by a hlgh ~re~uen~y aarrier, then lt oannet he an ~F channel oacupl-d by l~s own tran~mltter, wl~hou~
~equlring evaluatlon o~ the telegram addre~ in the ~eaeiver to prove thl~.
F DESCRIPTION OF ~H~ WING
Two examples o~ method~ wlll be d~8ari~e~ ln d~t~il below ln con~un~tlon with the drawlngs.
Fig. 1 iB a bloak alrault diagram o~ ah E~P
tran6aelver ~y~tem.
Fig. 2 1~ a ~lowahar~ of a fir~t mo~e of operatlon, "~eaeiver ~earche~ for tran~mitter ~hannel".
Fig. 3 i~ a ~l~w~har~ ~ a ~eeona mode o~ operatlon, ~recelver ~earahe~ Por Preo channel".
DESCRIPTION OF TH~ ~REEER~E~ ~M~O~IM~NT8 The tran~mltter S ~hown in Fig. 1 comprl~eB a high-~requenay tran~mission p~rt HF~, whose h~gh-~requenoy channel can be ~elected by the u~er by mean~ of a programming logl~ P.
The recelver ~ ~iret, in A ~nown manner, comprl~e~
the actual recelver part HFR ~ollowed b~ the telegr~m deooder ~EC, whose output slgnal ~ trip~ th~ de~ired funa~lon oP a aontrolled maohtne.

.... ~.. ~.. ~ .

2~9~283 PATENT

~ he ~quelch output o~ the reoelver pArt ~FR and the addre~ output of the nddre~ deaoder DE~ are ~upplled vln re~pea~lve l~ne~ BQ an~ ADR to a 3aannln~ oirouit ~AN, which ln turn oan ~wltch over the reoelve ohannel o~ the reaelver unit HFR vla a control line ~H.
~ he ba~ic funatlon o~ the saanning ciroult 9~AN 1B
that the squelch signAl on the line SQ ~ preferentlally evAluAted, and only ~f~e~ that i~ the ~'nddre~ ma~che~"
ln~ormation on the add~eqe ~eedback llne ADR oP the lo Addre~ de~oder ~C evalu~ted.
~ f the ~quelch ~lgn~l lndicate~ that thR~e 1~ no hi~h-frequenay ~ignal pre~ent on the tuned-~n recelve ohannel, then the 3cannlng cl~auit SCAN chan~e6 the ahonnel to whlah receiv~r R i~ tuned onw~rd by one channel via the control line ~H, lf th~ clrauit i8 ln~ended to perform the "~eaeiver 6earche~ ~or tranemitter ahannel~' Pun~tlon, or ~end~ feedh~ck in~rmAtion to the ~ran~m~t~er if the receivQr iB
lnten~ed to perform the ~receiver 6earche~ ~or ~ree ~0 ahanhel" fuhction, ~lnoe 1~ 1~ p~eci~ely ~he ab~ence of the squelah ~ignal that lndicates the presehae of a ~ree ahannel.
~ he scAnnlng airauit S~AN may typlaally lnclude A
memory deviae, for example ~ ROM, for storing ~ddre~
in~ormAtion. ~he pre~oncQ or Ab~enao o~ A 6quelah ~lgnAl on line SQ can be repre~ented by the value o~ A ~lngle binary bit whlah can ~e ea~ily aaded to the ad~re~
output on line A~ or can be ~upplled ~epar~ely ~o soanning cir~ult ~CAN to 8Upply a signa~ to con~rol line C~ ~or the purpo~e oP changlng the tuning o~ rece~er unit HF~.
Modlflaatlon of exis~ing ~o~hhing oircuit hardware and/or ~oftw~re to re~pond to the squelch output of a reaeiver unit aan ea~ily be efected by ~ho~ skill~d in the radio communicAtlon~ R~t on the ~aGL~ o~ existing teohniaAl kn~wledge in that art.
The~e two exemplAry mod~s o~ oper~tion, u~ing the ~aannlng ~ixqult SCAN and the evalua~lon o~ ~he ~quelch ~lgnHl, are shawn in ~he two flowohart~ e~etched ln Figs.
2 and 3. In the proce~ure o~ Fig. 3, ~fter a low squelch ~A~
PD-273~

signal vAlu~ i~ deteoted, the receiver remalns tuned to the ~ree ah~nnel.
Both exemplary modea oP operAtlon c~n be r~allzed wi~h the GAme tran~mit~er/recei~er-arrangement. ~ovever, a~ the re~ponse of the ecanning aircuit S~AN (changing the channel) depend~ on the ~lgnal ~tate o~ the equelch-~ignal ln the re~pective mode of opQrAtion~ it ie then nece~ary to provide ~or n po~ibillty to change the reepon~e oP the eoannlng cirault ~changing the channel) to ~be ~ignal ~tate of the ~quelch-s~gnA~ ~hlgh/low), which may be realized by a swlt~h ~tlvAted manually or automatically, onae one of ~he operation~ ha~ been te~mlnated.
In the ~ro~edure shown in Fig. ~, the Psedbaok l~ inPormation ~ent fr~m the receiver to the tran~mltter aontaln~ at lea~t a dlgltAl ~i~nal wh~ch can elther produce, at the tr~n~mltter, an indication to the t~an~mitter operator that the ~xanemi~610n ~equency mu~t be changed, or a command whlch cau~es ~he t~Anemltter to ao automaticAlly change lts tran~mlssion Prequenay. The ~eed~ac~ ln~ormation m~y lndlcate, ln aonneo~ion wlth elther manual or A~tomatl~ trnnemltter cont~ol, ~ha~ ~he tran~mitter ehould ~wltch to the next transml~slon f~equen~y, o~ ahannel, or that the ~ran~mltter should swltoh dlreatly to the ~ran~ml~lon ~requency which the re~elver found to be ~le~r.
In the mode o~ operatlon deplcted in Fig. 3, a~ter the receiver rind~ A ~req~enoy, or channel, to be clear, lt remaln~ tun~d to tha~ ~r~quona~.
It will be Appre~:iAtl3d that ~o implement the operAtlon deplc~ed ln Flg. 3, receiver ~ mu~t be equipped with a txan6ml~ion unit, S~ in HFR, and tran~mi~er S
mu~t be equipped with A receiving unit~ R' in ~FS, ~oth ~f which may be tuned ~o an otherwlse unused HF channel, Thi~ applio~tion relates t~ ~ub~ect ~atter dioclo~ed in Ger~an Appliaation number P 42 14 627.5-32, $iled on M~y a, l~g2, the dioclosure o~ whlch i5 inc~rpor~ed herein by ~e~erenoe, While the d~s~rlp~lon a~ove refex~ to partiaul~r e~odiments of ~h~ pxe~en~ invention, it will be 2as~s3 PATENT

under~tood that ~any mo~l1catlon~ may be made wlthout departlng from the oplrit thereo~. Th~ Aaao~panylng ol~im~ are lntended t~ cover ouch modlPlcAtioh~ ould fall wlthln the true ecope and ~plrlt o~ the present inventlon.
The pre~ently dl~alo~ed embodimento are ~here~ore to ~e aonsidered in all re~peot~ A~ lllu~trative and not restrictlve, the ~a~pe o~ ~he inventlon b~ng indlcated by the appen~ed clalmo, ~ather than the fore~o~ng 10 descrlptloh, and ali ahangeo whlah come wl~hln the meaning and rangR o~ equlvalenay oP the olaim~ are there~ore lntended to be embraced therein.

Claims (3)

1. In a method for establishing an interference-free radio connection between transmitting means for transmitting high frequency signals at a plurality of radio frequencies and a receiver tunable to each one of the radio frequencies, which method includes:
transmitting, from the transmitting means, control messages at at least one of the radio frequencies, each control message including and address sequence specific to the receiver;
turning the receiver to one of the radio frequencies; and determining whether the signal at the radio frequency to which the receiver is tuned contains the address sequence specific to the receiver, the improvement comprising:
deriving, in the receiver, a squelch signal having a first signal state when a high frequency signal is prevent at the radio frequency to which the receiver is tuned, and a second signal state when a high frequency signal is not present at the radio frequency to which the receiver is tuned; and returning the receiver to another one of the radio frequencies in response to a selected signal state of the squelch signal.

2. A method as defined in claim 1 wherein said steps of deriving and returning are preformed repeatedly for respectively different radio frequencies until a squelch signal having the first signal state is derived, and said step of determining is performed only after the receiver is tuned to a radio frequency for which the squelch signal has the first signal state.

3. A method as defined in claim 1 for searching an interference-free radio frequency upon the occurrence of a radio connection having interference, comprising:
turning the transmitting means off:
performing said tuning step through a plurality of radio frequencies until the receiver is tuned to a radio frequency at which a squelch signal having the second signal state is derived;
sending from the receiver to the transmitting means a signal for activating the transmitting means; and causing the transmitting means to transmit signals at successive ones of the radio frequencies until transmission occurs at that one of the radio frequencies at which the squelch signal had the second signal state in said performing step.