JPH03140884A - Method and device for measuring relative delay - Google Patents

Abstract

PURPOSE:To measure a relative delay by one test by impressing first and second test signals synchronously on the respective ends of first and second transmission channels respectively and by forming a delay difference signal by combining these test signals with each other. CONSTITUTION:When test signals T1 and T2 are impressed on transmission channels, a difference signal DS is generated at the output of a difference detec tor. First, in a first section of the difference signal DS, a waveform SD which is a difference (SS1-SS2) of sweep signals appears in a period I2. When the difference is zero, this waveform SD becomes a flat line of 0 volt. When there is a relative delay, the waveform SD becomes a sine wave having an envelope EV3 of frequencies rising continuously. A size X at an arbitrary point in a period I3 of this envelope EV3 relates to the size of a delay difference at a sweep frequency fx to which it corresponds. It is a delay marker DM1, for instance, in a section following the above that scales the size X of the envelope EV3 in a delay time, and this marker is obtained from a difference between a first marker component DM1a and a second marker component DM1b corre sponding thereto.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to the measurement of the relative delay of two transmission channels, and in particular to the measurement of the relative delay of two transmission channels, and in particular to the measurement of the relative delays of two transmission channels, and in particular to the measurement of the relative delays of two transmission channels. The present invention relates to a method and apparatus for measuring relative delay between two transmission channels transmitting signals.

Prior Art U.S. Pat. No. 4,829,366 (Method and Apparatus for Measuring Delay Difference/Gain Difference Using Two Different Frequency Sources) includes
Techniques are disclosed that can be applied to measure relative delay and gain differences between transmission channels. This technique uses two burst packets, each consisting of a periodic signal, as test signals. The periodic signals of these packets have frequencies that differ by a certain small frequency around representative frequencies within the frequency band of the transmission channel being tested (e.g. 500KH2 and 502KH2), and may be L. The phases are made to match each other at a predetermined time position within the packet. These test signals are passed through the transmission channel under test and the resulting periodic signals are subtractively combined to generate a beat whose waveform is displayed on an oscilloscope. In this technique, the delay difference between two transmission channels is determined by the amount of deviation in the time axis direction of the minimum amplitude point of the beat waveform from the predetermined time position, and the gain difference is determined by the magnitude of the amplitude of the minimum amplitude point. It can be measured as a

Another technique was disclosed in the above US patent at the International Broadcasting Conference (I) held in Printon, UK in September 1984.
international BroadcastiB
James and Marshall, “Measurements in a Television Component Environment” (Measurements in a Television Component Environment)
evision ComponentEnvironm
ent by A, ass snd P, J, Mir
It is mentioned in a paper titled ``shall''. This technique measures the delay difference between transmission channels by applying a 500 KHz sine wave signal to one or two transmission channels simultaneously, displaying the resulting signal on a dual-trace oscilloscope, and measuring the sine wave outputs. The idea is to check whether the zero crossing points of the waveform are aligned with each other.

Problems to be solvedAs is known, TV analog components,
Each component signal in the system (Y, B-Y,
RY (or R, G, It) typically has a bandwidth of 5 to 6 MH2. The two conventional techniques described above measure the transmission characteristics of the transmission channel of each component signal only at one representative frequency (ie, 500 KHz) within this frequency band.

However, each component signal is 500KHz
Frequencies other than the above may also experience various delays, and the amount of delay may vary greatly over the above frequency band.

The main reason for this is the component type VTR used in TV broadcasting stations, TV production, etc., which forms the transmission channel, due to the digital processing of component signals.
These are various high-pass filters installed in switchers, encoders, etc. These filters are designed to cut frequencies above a certain level related to the sampling frequencies due to limitations imposed by various sampling frequencies related to digital processing.

However, with the above conventional technique, in one test,
The delay difference cannot be measured over the entire frequency band, nor can the change in the delay difference over the frequency band be easily known.

SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to provide a measurement method and apparatus that allows the relative delay of a signal between two transmission channels to be easily found over a frequency band of interest.

Means and Effect for Solving the Problems In order to achieve the above object, the present invention provides a first and a second transmission channel for measuring relative delays of signals at different frequencies in two transmission channels. First and second test signals are synchronously applied to one end of each of the channels, respectively. The first and second test signals each include a measurement signal that includes a frequency portion equal to the plurality of different frequencies and has an amplitude of a predetermined envelope waveform in order to measure the magnitude of relative delay. I'm here. next,
receiving the first and second test signals resulting from transmission from the other end of each of the transmission channels, and combining the test signals with each other at each of the plurality of frequencies received during propagation on the transmission channel; to form a delay difference signal having an amplitude representative of information regarding the magnitude of the delay difference at .

This allows the relative delays of transmission channels to be measured at multiple frequencies in a single test.

According to the present invention, it is further possible to display the waveform of the delay difference signal.

Further, according to the present invention, the first and second test signals include a marker for providing a reference regarding at least one of polarity, magnitude, and frequency regarding the delay difference represented by the amplitude of the delay difference signal. can be made to include.

Further, each said test signal may have first, second, third and fourth signal portions. The first test signal portion consists of an interval of a predetermined length, and in order to measure the magnitude of the delay difference, the measurement signal is As,
It may include a sweep signal of the amplitude of the predetermined envelope waveform whose frequency changes in a predetermined frequency range. The second test signal portion consists of at least one said interval, said one interval including a delay marker for providing a scale as to the magnitude of said delay difference, in a predetermined period part of said interval; can be made to include. Said third test signal portion consists of one said interval, said interval including a frequency marker for providing a scale as to the frequency at which said delay difference is occurring, in said predetermined period part of said interval; can be made to include. The fourth test signal portion may consist of one section including a polarity marker for measuring the polarity of the delay difference.

5 6 According to the present invention, the above display is the 11th second, third
, and the waveforms of the delay difference signal in each of the sections forming the fourth test signal portion may be displayed in an overlapping manner.

Further, according to the present invention, in the first test signal portion, the first and second test signals may include the same sweep signal. The second test signal portion is
The predetermined period portion may include the delay marker indicating the same one delay time reference value over the predetermined frequency range, the delay marker being l) the first
ii) a second delay marker component included in the second test signal, the delay marker component exhibiting the same first delay time reference value over the test signals; and ii) a predetermined delay marker component over the second time period, which has the same magnitude over a predetermined frequency range over the predetermined time period with respect to the first and second waveforms. and the second delay marker component, which is adapted to represent a waveform of The third test signal portion may have the frequency marker indicating at least one frequency within the predetermined frequency range within the predetermined time period portion, the frequency marker being included in the predetermined test signal. the frequency marker component indicating a delay time reference value of two predetermined constant levels;
ii) M2 frequency marker components comprised of impulses included in said second test signal, the positions of said impulses within said predetermined period portion being equal to said predetermined frequency marker components of said corresponding frequency portion within said sweep waveform; and the second frequency marker component coincident with a position within a period portion of . In the fourth test signal portion, the first and second test signals may have the same waveform as the first and second components of the polarity marker, respectively.

Next, one embodiment of a measuring device in which the present invention is applied to a (Y-B-Y-R-Y) analog component system (AC8) will be described.

FIG. 1 shows three transmission channels 1. for each of the Y, B-Y, and R-Y component signals for AC3.
2.3, which correspond to input terminals 4.5 and 4.5, respectively.
．． 6 and output terminals 7.8.9.

This measuring device consists of a signal generator 10, a difference detector 12, and a waveform display 14. The signal generator 10 is F
It has a ROM, and generates a pair of test signals T1 and T2, which will be described below, from this memory programmed in advance from the outputs of CH-1 and CH-2. In the illustrated example, the test signals TI, T2 are input to input terminal 4 of Y channel l.
, B-Y channel 2 input terminal 5, respectively.

The test signals Tla, T2a of the transmission results obtained from the output terminals 7.8 of these transmission channels are
The detector 12 calculates the difference between these signals, that is, (Tla - T2a),
A difference signal DS is generated at the output. The next waveform display 14 is
The waveform of the difference signal is displayed on the screen.

As the difference detector 12 and waveform display 14, a conventional oscilloscope or waveform monitor with a function of observing the difference between CH-1 and CH-2 can be used.

Next, with reference to FIGS. 2A and 2B, the test signal T1
, T2, and the difference signal DS will be explained in detail.

The illustrated signal has a level value for the MI format. In addition, in those figures, the signals are shown on the same time axis.

The test signals T1, T2 are broadly divided into four test signal parts SPI, SF3, SF3, and sp4, and each signal part consists of one or more horizontal lines (H).
It has the length of the interval.

Each H interval (length of 63.5 microseconds) consists of the first half period 11 (in this example, 16.8 microseconds) from the start time to to tl including the horizontal synchronization pulse, and the remaining period from tl. The second half period is divided into 12 periods (46.7 microseconds in this embodiment).

SPI is a delay measurement signal portion consisting of one section. In this part, both test signals Tl and T2 are delayed from the transmission channel during period I3 from tl to t2 (61.2 microseconds in this example) within period I2. Sweep signals SSI and SS2 are provided as signals for delay measurement. However, since this test signal is for the Y-B-Y-RY analog component system, the signal T2 does not include a horizontal synchronization pulse.

These sweep signals SS have amplitude peak-to-peak values of 0.
Constant value of 7 volts (i.e. envelope EVl, EV2
is flat), and the packet (rectangular part surrounded by a solid line) consists of a sine wave (note: the figure is simplified) whose center level is 0.35 volts. This sweeping sine wave has a frequency from fl (=200KHz) to f2 (
= 5.5 MH continuously, and the frequency sweep speed changes in a constant linear manner. The swept sinusoidal waves SS1 and SS2 in the signals T1 and T2 are made to perfectly match each other in amplitude and phase so that their difference is zero.

The next SP2 to SP4 are marker forming signal parts, and S
F3 is the delay marker forming signal portion, SF3 is the frequency marker forming signal portion, and SF3 is the polar marker forming signal portion.

First, the delay marker forming signal portion SP2 is a portion that provides a scale of the relative delay amount, and in this embodiment,
Delay Ons marker DMI, delay 20ns? -force DM2,
40ns delay marker DM3 and 60ns delay marker D
It consists of four sections to form four markers of M4. Each marker has a first marker component a in the period I3 of the corresponding section of the test signal Tl, and a second marker component a in the same period 3 of the corresponding section of the test signal T2.
formed from.

The first components DM1a-DM4a of each marker are all waveforms at a constant level of 0.7 volts in the test signal T1. On the other hand, in the test signal T2, the second
The component DM1b is also a waveform with a constant level of 0.7 volts so that the difference with DMla is zero. The second component DM2b of marker DM2 is Vl port (
-0,6912 volts to v2 port (=0.4629
volt), the difference from DM2a is the sine wave S1, which will be described later.
This is a waveform that changes along a curve C1 that forms part of the curve C1. The second component DM3b of the next marker DM3 is v3 port c=
0.6824 volts) to V4 Porto (-0,2538
volt), the difference from DM3a is sine wave S2, which will be described later.
The second component DM4b of the last marker DM4 changes from ■5 volts (=0.6736 volts) to ■6 volts (-0,
0975 volts), the difference from the same <DM4a consists of a waveform that changes at a curve C3 that forms a part of a sine wave S3, which will be described later.

Here, the above sine waves S1 to S3 will be explained with reference to FIG. Each sine wave is approximately 2A sin (θ/2
) (]), where A is the amplitude (=0.35 volts) of the swept sine wave SS. θ is expressed as θ=2π(td)f (2), where td is the delay time difference between the test signals TI and 12. Equation (+) is one of the sweep signals of the test signal T1.
The signal at the frequency of a point is expressed as As1nωt, and the signal at the frequency of the same point of the sweep signal of the test signal, which is relatively delayed by an angle θ, is expressed as As1n(ω[-θ)
The difference is calculated.

Therefore, the sine waves 31% S2 and S3 are each 20% in td.
Substituting ns, 40ns, and 60ns, formulas (1) and (2
). Note that the analog
For component systems, 0.2 to 5.5
A MHz curve is used. These curves C1, C2, C
3 appears in the difference signal DS at the bottom of FIG. 2, and these act as a scale regarding the magnitude of the delay difference.

Next, the frequency marker forming signal portion SP3 will be explained. The frequency marker FM provides a scale related to the frequency of the delay difference, and in the period I2 of one section forming this signal part, the first marker component FM a included in the test signal Tl and the first marker component FM a included in the test signal T2. and a second marker component FMb. First marker component F Ma
consists of six impulses of increasing height 3 = 24-. In this example, these impulses are 0.5.1°2.3.4.
Since the markers are 5 MHz, their positions in the time axis direction within the period 3 are made to match the positions of the corresponding frequency portions of the swept sine wave SS within the period I3. Second
The marker component FMb of is constant as shown in the figure, i.e., O
This is the waveform of Porto.

Finally, the polarity marker forming signal portion SP4 consists of one section, and is a portion for forming a polarity marker PM for indicating the sign of the magnitude of the delay difference between the test signals TI and T2. . This part is t3 (e.g. 9.8 microseconds) in the first half period 11 of test signals TI and T2.
first and second marker components PMa1PM consisting of identical square pulses from to t4 (e.g. 14.8 microseconds)
Contains b. This rectangular pulse has a rising and falling frequency of 1 within the sweep frequency range.
It is desirable that the frequency of the point be close to the lower limit frequency f1.

The operation of this measuring device using the test signals TI and T2 explained above will be explained next.

As a result of this measurement device applying these test signals to transmission channel 1.2, a difference signal D as shown in the lower part of Fig. 2 is generated.
S is generated at the output of the difference detector 12. It is assumed that these transmission channels 1 and 2 have already been adjusted so that the gain difference between them becomes zero. Furthermore, in the illustrated difference signal, it is assumed that the amount of delay in channel 1 is smaller than that in channel 2.

First, in the first section of the difference signal DS, a waveform SD, which is the difference between the sweep signals (SSI-3S2), appears in period 12. This waveform SD becomes a flat line of 0 ports when the difference is zero. On the other hand, when there is a relative delay as in the illustrated example, the waveform SD becomes a sine wave with an envelope EV3 in which the frequency increases continuously. The size X at any point within the period I3 of this envelope EV3
is related to the magnitude of the delay difference at the corresponding sweep frequency fx.

The size X of this envelope EV3 is scaled to the waveform of the delay marker D of the next second to fifth section.
MI-DM4, which are the corresponding first marker component DM1a=DM4a and second marker component DM1b-DM4.
What can be obtained from the difference in b is as described above. Note that the relative delay between the first and second components of these delay markers can be substantially ignored. Therefore, the above envelope EV3 is, for example, 20 ns when the delay difference is a constant value of 20 ns over the entire sweep frequency range.
This coincides with the curve C1 of maca DM2.

The frequency marker FM in the next sixth section and the polarity marker PM in the seventh section are also obtained from the difference between their first components FMa, PMa and second components FMb, PMb, as described above. Regarding the polarity marker PM, it is assumed that the delay of the test signal T2 is greater, so the positive impulse comes first and the negative impulse follows. The opposite is true if the delay of T2 is smaller.

A display example when the above difference signal DS is displayed on the waveform display 14 is shown in FIG. As can be seen, the difference signal DS
The waveforms of the seven sections are displayed superimposed on each other (
Note: For clarity, some of the displayed waveforms have been omitted.) Based on this display, the polarity and magnitude of the relative delay in the frequency range f1 to f2 can be known. Based on this display result, an equalizer (not shown) provided within the transmission channel can be adjusted to bring the relative delay between the transmission channels within an acceptable range.

The following modifications can be made to the embodiments of the invention described above.

First, the number of sections of the signal portion SP2 of the test signal can be changed depending on the number of delay markers desired to be displayed. In addition, in order to reduce the number of sections required for each test signal, we use polar markers, Ons delay markers, etc. that do not interfere with each other.
The frequency marker can be formed in one section.

Second, the envelope EVI of the sweep signal 5S11SS2
SEV2+4, 7 8 on the low frequency side of FIG. 4 To make it easier to read, the amplitude can be changed so that the amplitude is maximum at frequency f1 and decreases toward frequency f2. In this case, a corresponding change may be made to the delay marker to make the slope of the delay marker more gentle.

Third, the frequency sweep rate of the swept sine wave can be changed to be a logarithmic sweep. In this case as well, the delay marker and frequency marker may be changed accordingly.

Fourth, the first component for forming a delayed marker (DM 1a=D
The waveforms of M4a) and the second component (DMI b-DM4b) have a difference of zero, curves CI, C2, and C3, respectively.
It can be arbitrarily changed as long as it forms.

Fifth, the sweep format of the sweep signal can be changed from a continuous sweep to a stepped sweep, so that a sine wave of one frequency continues for a certain period of time before moving to a sine wave of the next frequency. Corresponding changes in the retardation markers and frequency markers will also be obvious to those skilled in the art.

Sixth, the test signal can be repeated back to the first interval after the seventh interval ends. Another iteration method is to repeat each interval many times before moving on to the next interval. In this case, for example, in each field of the video signal, the first section is repeated for 100H (horizontal line), each of the second to fifth sections is repeated for 15H, the sixth section is repeated for 41H, and the seventh section is repeated for 15H (horizontal line). can be repeated for 41H.

Seventh, the present measurement method and apparatus are useful for other R-G-B analog component systems and for other B-analog component systems.
It can be similarly applied to the ejacam video format with slight modifications.

According to the measurement method and apparatus of the present invention described in detail above, it is possible to know the relative delay in a large number of different frequencies or in a frequency range of interest by a single measurement, and the measurement result can be used to make fine adjustments to the characteristics of the transmission channel.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the transmission channels of an analog component system as well as a measuring device according to the invention. FIGS. 2A and 2B are waveform diagrams showing, on the same time axis, the waveforms of a set of test signals used by the measuring device of the present invention and a difference signal generated therefrom. FIG. 3 shows a sine wave from which different curves for delay markers are obtained. FIG. 4 is a waveform diagram showing an enlarged display example of the difference signal shown in FIGS. 2A and 2B on a waveform display. (Description of symbols) 1.2.3: Transmission channel, 4.5.6: Input terminal, 7.8.9: Output terminal, lO:
Signal generator, 12: Difference detector, 14: Waveform display, T1, T2: Test signal, Tla, T
2a: Test signal of transmission result, DS: Difference signal, SPI to SP4: First to fourth test signal portion, period, 551, SS2: Sweep signal, waveform of 5III sweep signal sweep difference, EVI, EV2, Ev3: Envelope, fl: lower limit sweep frequency, T2: upper limit sweep frequency, DMI to DM4: delay marker, DMI a = DM4 a: first component of each delay marker,
DMI b - DM4 b: the second component of each delay marker,
81 to S3: sine wave, C1 to C3: delay marker curve, FM dual frequency marker, FMa, FMb: first and second components of frequency marker, PM: polarity marker,

Claims (1)

[Scope of Claims] A measurement method for measuring the relative delay of signals at a plurality of different frequencies in one or two transmission channels, comprising: (a) a second transmission channel at one end of each of the first and second transmission channels; synchronously applying first and second test signals, each of which has a frequency equal to the plurality of different frequencies in order to measure the magnitude of relative delay; b) measuring the first and second test signals as a result of transmission from the other end of each of the transmission channels; receiving and combining the test signals with each other to form a delay difference signal having an amplitude representative of information regarding the magnitude of delay difference at each of the plurality of frequencies received during propagation on the transmission channel; A relative delay measuring method, comprising: measuring relative delays at the plurality of frequencies of the first and second channels using the delay difference signal. 2. The relative delay measuring method according to claim 1, further comprising the step of displaying a waveform of the delay difference signal. 3. The method according to claim 2, wherein the first and second test signals provide a reference regarding at least one of polarity, magnitude, and frequency regarding the delay difference represented by the amplitude of the delay difference signal. A relative delay measurement method characterized by comprising a marker for. 4. The method according to claim 3, wherein each of the test signals has first, second, third and fourth signal portions, and a) the first test signal portion comprises one In order to measure the magnitude of the delay difference, the frequency of the measurement signal is within a predetermined frequency range during a predetermined period within the section. (b) the second test signal portion is comprised of at least one said section, and said one section is comprised of a sweep signal with an amplitude of said predetermined envelope waveform varying with said delay difference; c) said third test signal portion consists of one said section, said section comprising: a delay marker for providing a scale with respect to said interval; d) the fourth test signal portion includes a frequency marker for providing a scale regarding the frequency at which the delay difference occurs in the predetermined period portion of the section; and d) the fourth test signal portion indicates the polarity of the delay difference. A method for measuring relative delay, comprising one section including a polarity marker for measurement. 5. The method according to claim 4, wherein the displaying step displays the waveforms of the delay difference signals in each of the sections constituting the first, second, third, and fourth test signal portions in a superimposed manner. A relative delay measurement method characterized by: 6. In the method according to claim 5, a) in the first test signal portion, the first and second test signals include the same sweep signal, and b) the second test signal The test signal portion of includes the delay marker indicating the same one delay time reference value over the predetermined frequency range in the predetermined period portion, the delay marker comprising: i) the first delay time reference value; ii) a first delay marker component comprised of a predetermined first waveform included in the test signal; and ii) a second delay marker component included in the second test signal, the second delay marker component being comprised of a predetermined first waveform. On the other hand, the second waveform has a predetermined level difference relationship over the predetermined period portion, and the level difference has a delay difference time of the same magnitude over the predetermined frequency range. c) the third test signal portion comprises at least one delay marker component within the predetermined frequency range within the predetermined period portion; The frequency marker includes: i) a first frequency marker component comprised of a waveform of a predetermined constant level, which is included in the first test signal; and ii) the frequency marker includes: a second frequency marker component comprised of impulses included in the second test signal,
the second frequency marker component, the position of the impulse within the predetermined period portion being coincident with the position within the predetermined period portion of a corresponding frequency portion within the swept waveform; and d) in the fourth test signal portion, the first and second test signals have the same waveform as the first and second components of the polarity marker, respectively. Characteristic relative delay measurement method. 7. A relative delay measurement device for measuring the relative delay of signals in two transmission channels at a plurality of different frequencies, comprising: a) first and second signals applied to one end of each of the first and second transmission channels, respectively; test signal generating means for generating a second test signal, each of the first and second test signals including portions equal to said plurality of different frequencies for measuring relative delay magnitudes; and (b) receiving the first and second test signals transmitted from each other end of the transmission channel. , signal processing means for combining the test signals with each other to form a delay difference signal having an amplitude representative of information regarding the delay difference at each of the plurality of frequencies experienced during propagation on the transmission channel. . A relative delay measuring device, comprising: measuring relative delays at the plurality of frequencies of the first and second channels using the delay difference signal. 8. The relative delay measuring device according to claim 7, further comprising display means for displaying the waveform of the delay difference signal. 9. The apparatus according to claim 8, wherein the first and second test signals provide a reference regarding at least one of polarity, magnitude, and frequency with respect to the delay difference represented by the amplitude of the delay difference signal. A relative delay measurement method characterized by comprising a marker for. 10. The apparatus according to claim 9, wherein each of the test signals has a first, second, third and fourth signal portion, and a) the first test signal portion comprises one In order to measure the magnitude of the delay difference, the frequency of the measurement signal is within a predetermined frequency range during a predetermined period within the section. (b) the second test signal portion includes a sweep signal with an amplitude of the predetermined envelope waveform varying by at least one
c) the third section includes a delay marker for providing a scale regarding the magnitude of the delay difference in a predetermined period portion of the section; The test signal portion of consists of one said interval, said interval including, in said predetermined period part of said interval, a frequency marker for providing a scale as to the frequency at which said delay difference is occurring. and (d) the fourth test signal portion consists of one section including a polarity marker for measuring the polarity of the delay difference. 11. The apparatus according to claim 10, wherein the display means displays waveforms of the delay difference signal in each of the sections forming the first, second, third, and fourth signal portions in a superimposed manner. A relative delay measuring device characterized by: 12. The apparatus according to claim 11, wherein a) in the first test signal portion, the first and second test signals include the same sweep signal, and b) the second test signal includes the same sweep signal. i) the test signal portion includes the delay marker indicating the same one delay time reference value over the predetermined frequency range in the predetermined period portion; ii) a first delay marker component comprised of a predetermined first waveform included in the test signal; and ii) a second delay marker component included in the second test signal, the first waveform being has a predetermined second waveform having a predetermined level difference relationship over the predetermined period portion, and the level difference has a delay difference time of the same magnitude over the predetermined frequency range. c) the third test signal portion is configured to represent at least one of the predetermined frequency ranges within the predetermined period portion; The frequency marker includes: i) a first frequency marker component comprised of a waveform of a predetermined constant level, which is included in the first test signal; and ii) a second frequency marker component comprised of impulses and included in the second test signal,
the second frequency marker component, the position of the impulse within the predetermined period portion being coincident with the position within the predetermined period portion of a corresponding frequency portion within the swept waveform; and d) in the fourth test signal portion, the first and second test signals have the same waveform as the first and second components of the polarity marker, respectively. Features: Relative delay measurement device.