Modes of Operation

TM 11-6625-922-15

Control, Indicator, or jack

Function

SWEEP CALIBRATE

Sw pos

Function

(3-position rotary) switch

SWEEP

Frequency of output signal

is swept, with a minimum

frequency set by CARRIER

FREQUENCY control,

sweep bandwidth set by

SWEEP WIDTH control,

and sweep speed set by

SWEEP TIME control.

LOW CAL

Output frequency is approxi-

mately lowest frequency in

sweep, with all other con-

trols remaining fixed.

HIGH CAL

Output frequency is approxi-

mately highest frequency in

sweep, with all other con-

trols remaining fixed.

SWEEP TIME control

Adjusts time it takes for output frequency to sweep

between lowest and highest frequencies, and also to

sweep down again from highest to lowest.

SWEEP WIDTH control

Adjust bandwidth of sweep frequency. CARRIER FRE-

QUENCY controls set lowest frequency, and SWEEP

WIDTH control effectively sets highest frequency.

TRANSMIT FREQUENCY-RECEIVE FREQUENCY

Selects output transmitted or input received signal fre-

(2-position toggle) switch

quency to be measured and indicated on REQUENCY

display.

COUNTING TIME (3-position rotary) switch

Selects time interval for counting pulses for frequency

measurement. Counts frequency in Hz in 1 SEC posi-

tion.

FREQUENCY display

Corresponds to frequency by indicating the number of

pulses within COUNTING TIME. The number is

displayed for about 1 second. When the COUNTING

TIME switch is in the 1 SEC position, the FRE-

QUENCY display indicates the frequency directly

in Hz. When in the .1 SEC position, the least signifi-

cant digit represents 10 Hz; when in the 10 SEC posi-

tion, it represents 0.1 Hz.

BAL TRANSMIT jack

Accepts telephone-type plug for sending balanced out-

put signal, with output impedance between 130 and

900 ohms.

75 Ω UNBAL TRANSMIT jack

Accepts BNC connector for sending an unbalanced out-

put signal, with an output impedance of 75 ohms.

TRANSMIT IMPEDANCE (5-position rotary) switch

Selects output impedance of the transmitted signal. With

75 (ohm) setting, 75 Ω UNBAL TRANSMIT jack

must be used. With other 4 settings, 130 to 900

(ohms), BAL TRANSMIT jack must be used.

SYNC pushbutton

Provides a means of synchronizing the effective phase

of the local receiver modulating frequency with the

transmitter modulating frequency in end-to-end meas-

urements, so that readings can be made near zero

(0) envelope delay.

Note. Figure 3-2 shows the signal connections on the rear panel connectors.

3-2. Modes of Operation

modulation frequency of the received carrier signal.

This is usually done with a transmitted carrier frequency

a. End-to-End. An end-to-end measurement is

in the range of anticipated minimum transmission delay

made over a single transmission line (fig. 3-3), because

of the line under test. The carrier frequency of the

no other lines are available for use as a return

transmitting TS-2669/GCM is then varied over the pass

reference.

A modulated carrier produced by the

band of the transmission line while noting the variation

transmitting TS-2669/GCM is sent down the line. At the

in line output level and delay time at the receiving TS-

receiving end of the line, a reference signal produced by

2669/GCM.

a receiving TS-2669/GCM is synchronized with the

3-3