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1 HP Archive This vintage Hewlett Packard document was preserved and distributed by www. hparchive.com Please visit us on the web! On-line curator: Glenn Robb This document is for FREE distribution only!

2 SGNAL SOURCE CHARACTERZATON USNG LOW COST FREQUENCY AND TME COUNTERS Dick Schneider Lyle Hornback 8369

WAVEFORM RECORDER SPECTRUM ANALYZER MODULATON

AGENDA Frequency drift, modulation sensitivity,

FDM signals Agile signals M-ARY FSK and frequency

settling time Timing measurements - aeronautical

BPSK Communication modulation transients Radar

3 WAVEFORM RECORDER SPECTRUM ANALYZER MODULATON ANALYZER FREQUENCY COUNTERS RECEVER ANALYZER 8370 AGENDA Frequency drift, modulation sensitivity, pushing and pulling figure Center frequency for FDM signals Agile signals M-ARY FSK and frequency hop Tuning transients - post tuning drift and settling time Timing measurements - aeronautical navigation Communication modulation - MPSK, QPSK, BPSK Communication modulation transients Radar parameters - chirp, frequency and phase coded Group delay 8371 WWWHPAR&VEcom

FREQUENCY DRFT, MODULATON SENSTVTY, AND PUSHNG AND PULLNG FGURES ~NViRONMENTAL' :.... ~CHAMBER TUNNG V T 1 _ SGNAL _ do -----+~-3 VOLTAGE 1" SOURCE P }".... 1 L.. POWER SUPPLY FREQUENCY t-h_p_-.

4 FREQUENCY DRFT, MODULATON SENSTVTY, AND PUSHNG AND PULLNG FGURES ~NViRONMENTAL' :.... ~CHAMBER TUNNG V T 1 _ SGNAL _ do ~-3 VOLTAGE 1" SOURCE P }" L.. POWER SUPPLY FREQUENCY t-h_p_-... COUNTER, , B~.CONTROLLER L.,..J,..--~--., 1 PLOTTER/ 1 L PRNTER The frequency drift, stability, modulation sensitivity, pulling and pushing figures, and synthesizer frequency setting may be easily measured with a low cost frequency counter. Modern microwave counters include a delta frequency reading where the difference between a stored reference frequency and current measurements are calculated and displayed. Of course data can be collected by a controller on the HP-B for plotting or print out. FREQUENCY DRFT L\F FREQUENCY STABLTY 6TME SYNTHESZER FREQUENCY SETTNG SET FREQUENCY 8373

8375 The center frequency of a microwave communications link that uses Frequency Division Multiplex (FDM) may be easily measured with a low cost frequency counter.

5 MODULATON SENSTVTY ~F PULLNG FGURE PUSHNG FGURE ~R=1.5/1 ~F '" LlF 8374 CENTER FREQUENCY OF FDM COMMUNCATONS SYSTEMS FREQUENCY COUNTER 11--~-_X_ E COMMUNCATON TRANSMTTER 1"'""1 1"'""1 PLOT TONE 1 MASTER GROUPS J D.U.V The center frequency of a microwave communications link that uses Frequency Division Multiplex (FDM) may be easily measured with a low cost frequency counter. For example a voice channel system of three master groups (1800 channels with 3.4 khz/channel plus bandwidth for multiplexing) requires approximately 8 MHz bandwidth. Pilot tones and Data Under Voice (DUV) may also be present in the low frequency baseband modulation. Absolute or center frequency deviations would be monitored with the frequency counter.

The frequency counter's wide instantaneous bandwidth allows for up to 1200 MHz at baseband andl50 MHz deviation to 50

6 AGLE SGNALS FREQUENCY AGLE SOURCE ---~E l. X ~ FREQUENCY COUNTER ~ - - CONTROLLER F! 8376 Many modern transmitters (and therefore La's and spot jammers) use frequency agility. The frequency counter's wide instantaneous bandwidth allows for up to 1200 MHz at baseband andl50 MHz deviation to 50 GHz (heterodyned). For signal sources exceeding 250 MHz deviation the frequency counters La can be programmed to reposition the 250 MHz window by the HP-B in less than 100 msec.

SYNC atc - NEXT WORD - FSK (-) -H 8378 M-ARY Frequency Shift Keying (MFSK) message modulation and frequency hopping diversity communication systems require the measurement of frequency during the

7 M-ARY FREQUENCY SHFT KEYNG AND FREQUENCY HOPPNG SGNAL ( SOURCE ~ X ~?... a r-... DATA BT EXT. GATE FREQUENCY COUNTER "ONE" OF 8 AND "ONE" OF HOP 8377 M-ARY FREQUENCY SHFT KEYNG AND FREQUENCY HOPPNG,,.--,,..., ~... ~ r--l : J F t ~ ~ ~ == H ~ ~ ~ ~ SYNC ' SYNC atc - NEXT WORD - FSK (-) -H 8378 M-ARY Frequency Shift Keying (MFSK) message modulation and frequency hopping diversity communication systems require the measurement of frequency during the data bit period Tc to determine proper frequency transmission according to shift keying and hopping deviations. One shot or repetitive (to increase resolution) measurements can be made by providing the data bit to the external gate of the frequency counter. (Assuming a "one" of data and hop gate signal.) 6

8 M-ARY FREQUENCY SHFT KEYNG AND FREQUENCY HOPPNG (AVERAGE) - F st 2nd 3rd 4th 5th 6th WORDS "ONE" OF_... DATA & HOP EXT. GATE SGNAL 8379 The resolution of the measurement may be increased by averaging the counts for each "one" of data and hop events. Measurement resolution improves by N, where N is the number of events. For example: Bit width = 100 J-sec J0 Single shot resolution =.+ee"khz Counter gate time = 100 msec N = 100 X 10-3 = X kh "3.'" Averaged Resolution = ffqooz =.&te4hz 1000

9 - TUNNG TRANSENTS POST-TUNNG DRFT AND SETTLNG TME SGNAL SOURCE FREQUENCY COUNTER EXT. GATE , STEP GENERATOR~S-Y-N-C ~ L.J GATE GENERATOR 8380 TUNNG TRANSENTS POST-TUNNG DRFT AND SETTLNG TME F t 8381 Transient measurements needed to evaluate a signal source are settling time and posttuning drift. Post-tuning drift is the change in frequency during the time interval t1 to t2, where t1 is a specified time after t<l>. the start of the step. Normally this measurement can be made the same as frequency drift. A profile of the frequency transient can be made by externally gating the counter from a gate generator synchronized to the step input.

TACAN, TCAS, ATCRBS, AND DABS TMNG TME RF ~ COUNTER ARCRAFT?

GATE GATE GENERATOR 8382 RF TACTCAL AERONAUTCAL ~AVGATON AR

TACAN NTERROGATON REPLY 12/36 J.LS ATCRBS NTERROGATON.

,, GATE START ARM STOP ARM REPLY 2 TO 15 PULSES ful.n 1.45 J.

pulse timing by externally gating the time counter.

10 TACAN, TCAS, ATCRBS, AND DABS TMNG TME RF ~ COUNTER ARCRAFT? SYSTEM MOO/OEMOO SYNC EXT. GATE GATE GENERATOR 8382 RF TACTCAL AERONAUTCAL ~AVGATON AR RAFFC CONTHOl SYSTEM l TACAN, TCAS, ATCRBS, AND DABS TMNG TACAN NTERROGATON REPLY 12/36 J.LS ATCRBS NTERROGATON.J1rLJlnnn : : 2 J.Ls J.Ls EXTERNAL.,, GATE START ARM STOP ARM REPLY 2 TO 15 PULSES ful.n 1.45 J.Ls 8383 Precision time measurements may be made of complex pulse timing by externally gating the time counter. For example, the 21 jj.sec delay of the ATCRBS interrogation signal can be measured if the external gate signal is applied as shown.

11 TACAN, TCAS, ATCRBS, AND DABS TMNG MOD HREAT ~OLLSON TeAS AND DABS AND ~VODANCE NTERROGATON REPLY YSTEM QSCRETE ~DDRESS JlJ1.JTTTTTTT1 eeacon YSTEM 2 J..Ls

$MPSK DGTAL PHASE MODULATON ReFaJiHC! Uf2, MPSK SGNAL -fco-" TME ~..." SOURCE ~U Q COUNTER ~,..to ~c.~,l\\.. DATA BT DELAY T EXT.$ ..-...r--+-+--1---t----t 225 ---+----...-+--~-...---+------.-... 135 1-----1to-...--+-~-----..-..------1...---i 451o-o.

..------i 270 1---+--+--+---+--+-- ~~---1"-""" 225 t---+---+----f--+-- '-----+---f 180 1---+---+-~---+O-04----~---+---+-~ 135

12 MPSK DGTAL PHASE MODULATON ReFaJiHC! Uf2, MPSK SGNAL -fco-" TME ~..." SOURCE ~U Q COUNTER ~,..to ~c.~,l\\.. DATA BT DELAY T EXT. GATE 8385 BPSK QPSK MPSK (8) DGTAL PHASE MODULATON ,.-----_-_--, ---, o i ~ f r t----t ~ to ~ i 451o-o f J---+--i 315 f if i--t i ~~---1"-""" 225 t f--+-- ' f ~---+O ~ ~ i_ i ~f O J-----'_~_--'----- ' '...&-- ' t Q -=---L -=-r: Q ~"' ~ i: Since = ~t time interval measurements can be made of the -Q signals to determine the phase modulation of the source. -Q demodulation techniques are described in another symposium paper or these signals may be available from the digital radio under test. 8386

$BPSK EXAMPLE 1 o START ARM 1-\..,', ;......' EXT. GATE. '... 1# DATA STOP...-1------- ARM MEASURED TME -.$

13 BPSK EXAMPLE 1 o START ARM 1-\..,', ;......' EXT. GATE. '... 1# DATA STOP ARM MEASURED TME -..ltm tm = 360 X T + NT where T = period of the F signal and N is the integer number of periods between start and stop arm. For example: F = 20 MHz, T = 50 nsec N = 3, 2 cycles data bit 1, 1 cycle data bit tm = 1/2 X X 50 = 175 nsec

GATEt TME SYNTHESZER ~l:m=k~tm T 8388 By gating the time counter with successive

14 MPSK DGTAL PHASE MODULATON TRANSENTS ~t: ~ (L6i, MPSK.+6'" TME SOURCE genl6& -e COUNTER SGNAL DATA BT (/)1«-0 ~/" EXT. GATEt TME SYNTHESZER ~l:m=k~tm T 8388 By gating the time counter with successive gate widths the time interval transient can be profiled in the same manner the step tuning transient or chirp pulse was measured.

15 RADAR PARAMETERS i~~~!~ , "', : -'-~_:._::-.&.:0... L-x...:~~.0;;..}_~... q" e, ~ "1 TEST PORT FREQUENCY COUNTER Y TEST HORN DETECTED PULSE OUT 8389 RADAR PARAMETERS PULSE BURST DETECTED PULSE PR '~ 8390 Modern microwave frequency and time counters measure the pulse burst frequency, the pulse width, and PRior PRF of radar signals.

CHRP PULSE FREQUENCY PROFLNG PULSEr-------------E CHRP SOURCE >< ~ 1

an external gating signal successively across the chirp pulse width.

16 CHRP PULSE FREQUENCY PROFLNG PULSEr E CHRP SOURCE >< ~ 1 TME FREQUENCY SYNTHESZER EXT. GATE COUNTER + F Lr-=====~-~ CHRP A r--rll BW f.-t~ ~ t ~ 8391 A radar chirp pulse frequency measurement is made by moving an external gating signal successively across the chirp pulse width. For chirp radar applications the modulation accuracy is paramount, while doppler radars require minimal FM on the burst.

17 FREQUENCY CODED RADAR RADAR SOURCE...-- SGNAL < ~ ---- EXT. TME GATE FREQUENCY SYNTHESZER COUNTER L_ --- E f X y J DETECTED PULSE OUT 8392 FREQUENCY CODED RADAR PULSE BURST DETECTED PULSE 3 FREQUENCY PULSE GROUP EXT. GATE u 8393

GATE u 8394 By positioning an external gate to the region of

18 FREQUENCY CODED RADAR FSK PULSE BURST.. 1"1 t' DETECTED PULSE _ FSK PULSE (BARKER CODED) EXT. GATE u 8394 By positioning an external gate to the region of interest, the pulse frequency from the group, or the FSK pulse frequency modulation can be measured.

$PHASE CODED RADAR,~ ~ ~~f RADAR SGNAL ~,..~o 'fa. SOURCE ~""\L PULSE DATA BT EXT. GATE TME COUNTER J1f1l.$ ..-1 ~-JLj~tm 8396 By arming the time interval measurement of the counter, in the same manner as for MPSK signals, the phase coded

..-1 ~-JLj~tm 8396 By arming the time interval measurement of the counter, in the same manner as for MPSK signals, the phase coded

19 PHASE CODED RADAR,~ ~ ~~f RADAR SGNAL ~,..~o 'fa. SOURCE ~""\L PULSE DATA BT EXT. GATE TME COUNTER J1f1l. TME SYNTHESZER 8395 PHASE CODED RADAR F PULSE BURST PULSE WDTH BPSK PHASE MODULATON rtlu ~ EXTERNAL GATE ~,.;...-1 ~-JLj~tm 8396 By arming the time interval measurement of the counter, in the same manner as for MPSK signals, the phase coded modulation can be measured. Varying the time delay from the start of the pulse and external gate width would enable demodulation analysis of the phase coded radar

with frequency fw CW(AM)-. > FREQUENCY..., ~ SOURCE..n.n.. MODULATON - d - /1 Tg= -= - dw /1w GROUP DELAY D.

20 GROUP DELAY W W1 cp1 = PHASE DELAY = T W1 GROUP DELAY = Tg - ~ == -/1 - dw - /1w 8397 Group delay Tg is proportional to the rate of change of phase shift with frequency fw CW(AM)-. > FREQUENCY..., ~ SOURCE..n.n.. MODULATON - d - /1 Tg= -= - dw /1w GROUP DELAY D.U.T. r>- A TME B COUNTER > MODULATON DETECTOR 8398

CW (RAMP) FREQUENCY SOURCE GROUP DELAY :> > --l D.U.T.

21 CW (RAMP) FREQUENCY SOURCE GROUP DELAY :> > --l D.U.T. L ~_r~ MXER TERMNATON FREQUENCY COUNTER 8399 F1 = kt F2 = k(t + T ) 1 F1-F2 = k T = k w1 ~ ~ (F1-F2). Tg == ~ == for short gate times uw k PULSE FREQUENCY SOURCE GROUP DELAY )~ D.U.T. r>- FAST DETECTOR MODULATOR A TME COUNTER -r AJn n n~ B -J.-T g 8400 B

22 Flin- HEWLETT ~~ PACKARD DATA SUBJECT TO CHANGE PRNTED N U.S.A.

HP Archive. This vintage Hewlett Packard document was preserved and distributed by www. hparchive.com Please visit us on the web!

HP Archive. This vintage Hewlett Packard document was preserved and distributed by www. hparchive.com Please visit us on the web! HP Archive This vintage Hewlett Packard document was preserved and distributed by www. hparchive.com Please visit us on the web! On-line curator: Glenn Robb This document is for FREE distribution only!