AVC Test Operating Mode

Last updated: October 28, 2004

Analog Voice Channel (AVC) test mode provides a forward voice channel for operating AMPS mobiles in test mode. This allows you to get the mobile transmitting on an AVC and test many functions in the mobile without the need to register or page the mobile.

AVC Test Mode Operation

When the test set's operating mode is AVC test mode:

No over the air signaling is available.
Changes to the test set's AVC channel assignment occur immediately.
When the test set's AVC channel is changed, the base station emulator is automatically reconfigured to receive the corresponding reverse AVC signal from the mobile. If needed, you can disable this operation by selecting manual receiver frequency control. See Receiver Control .
Changes to the MS TX Level automatically set the expected analog input power. If needed, you can disable this operation by selecting manual receiver power control. See Receiver Control .
SAT modulation of the test set's forward AVC can be turned on or off, and can be set to any of the three color code frequencies.
Internal FM of the forward AVC is available for various audio frequency tests.
An external FM source can be used to provide addition frequency modulation of the forward AVC.
The demodulated FM signal can be selected to output to the front-panel AUDIO OUT port for external analysis and baseband processing. See Configuring the Test Set's AUDIO OUT port .

Forward Channel FM Operation

Frequency modulation of the forward channel in AVC test mode is a combination of the SAT, internal FM, and external FM settings. No wideband data is present.

To meet specifications, the total peak FM deviation cannot exceed 20 kHz. Limitations for each FM source are as follows:

SAT - can be turned on or off, and has three color code selections: SAT1 (5970 Hz), SAT2 (6000 Hz), SAT3 (6030 Hz). Peak deviation is fixed at 2 kHz.
Internal FM - can be turned on or off, has a rate range of 100 Hz to 20 kHz, and a peak deviation range of 0 Hz to 20 kHz.
External FM - uses the test set's rear-panel FM Mod In port to connect an external modulation source. The fixed peak deviation for a 100 Hz to 20 kHz tone is 20 kHz/Volt.

AVC Test Mode Operation Using Automated Receiver Control

The following procedure demonstrates the use of AVC test mode where the base station emulator's RF generator frequency, measurement receiver frequency, and expected input power are automatically set by the call control settings used. This is the most common way to use test mode because it requires less individual configuration of call parameters.

This procedure provides general programming steps, but is not written around any specific test requirements. Some of the settings shown are the default power up settings for AVC Test mode.

Putting the mobile in analog test mode at the correct channel number and power setting is the responsibility of the user.

Select AVC Test mode.
OUTPUT 714;"CALL:OPERating:MODE AVCT"
Turn on the base station emulator's RF Generator and set the output level to -50 dBm.
OUTPUT 714;"CALL:POWer -50"
Set the AVC channel number to 777.
OUTPUT 714;"CALL:SETup:AVC 777"
Set the MS TX Level to two (2). (This is the mobile's power level setting, not the expected power in dBm.)
OUTPUT 714;"CALL:SETup:MS:ANALog:TXLevel:CELLular 2"
Turn the forward channel AVC SAT on.
OUTPUT 714;"CALL:AVCTest:AVC:SATone:STATe ON"
Set the SAT color code to SAT1 (5970 Hz).
OUTPUT 714;"CALL:SETup:AVC:SATone SAT1"
Turn on internal FM, and set the deviation to 8.0 kHz and the rate to 1004 Hz.
OUTPUT 714;"CALL:FM:INTernal 8 KHZ;INT:FREQuency 1004 HZ"
If you do not want internal FM on, use the FM State command to turn it off:
OUTPUT 714;"CALL:FM:INTernal:STATe OFF"
Turn external FM off.
OUTPUT 714;"CALL:FM:EXTernal:STATe OFF"
Connect the mobile's antenna port to the test set's RF IN/OUT port and put the mobile in analog test mode, transmitting at power level two on channel 777.

If your mobile's audio is not muted, you should hear a 1004 Hz tone out of its speaker. If you have an acoustic or direct connection to the mobile's audio output, you can make audio measurements through the test set's AUDIO IN connections. See Audio Analyzer Measurement Description .

You can also make analog transmit power and frequency stability measurements on the mobile's reverse channel carrier. If you modulate your mobile's carrier, you can measure the frequency modulation characteristics. See Analog Transmit Power Measurement Description , Frequency Stability Measurement Description , and Frequency Modulation (FM) Measurement Description .

AVC Test Mode Operation Using Manual Receiver Control

Note: Changing the operating mode affects manual receiver control parameters. See Effects on Receiver Control When Changing Operating Mode .

The following procedure demonstrates the use of AVC test mode where the base station emulator's RF generator frequency, measurement receiver frequency, and expected input power are manually configured. Manual control is not commonly used in production testing, but is provided to allow the measurement receiver and RF generator to be used to perform tests where automated control may not be used; such as when tuning the receiver to make measurements outside of the cellular band during AMPS testing.