If you are attempting to verify a manufacturer's specification, the TIA-603 procedure should be used. If you are serious about that, you should probably acquire TSB-88 in addition to TIA-603.
Here is a link to a presentation that discusses adjacent channel testing and explains the roles of the various standards documents: http://www.apcointl.org/frequency/documents/W09-olson.ppt Jeff has summarized the procedure correctly with the exception that the current procedure utilizes a two-tone modulation for the interefering signal. This test requires that the signal generator ustilized for the interefering signal have exceptional phase noise performance or the test results will be inaccurate. There are a number of suitable high-end generators such as the Aeroflex 2041. I doubt if the signal generation function of any service monitor is suitable. If you are simply wanting to compare various recever models for a particular application such as a repeater receiver, an alternative would be to use the actual repeater transmitter as the interferer. Connect it to a suitable load with a signal tap and attenuator configured to sample the signal and feed into the receiver test in place of the second signal generator. Here is another summary of a process similar to the TIA-603: ADJACENT CHANNEL REJECTION Method of Measurement Terminate the audio output of the receiver in a load specified by the manufacturer, and make measurements using a C-message weighted filter. (a) Connect two RF signal generators equally coupled to the receiver antenna input terminals through a suitable matching network. Set the first RF signal generator to the assigned channel frequency and modulate it with a 1004 Hz tone at 60% of the maximum permissible peak frequency deviation. Switch the second generator off. Adjust the first RF signal generator level to produce a 12 dB SINAD measurement at the audio-output terminals of the receive path. Record the RF signal level and increase this first RF signal generator output by 3 dB. (b) Set the frequency of the second RF signal generator to the adjacent channel above the frequency of the first RF signal generator and modulate it simultaneously with two tones, one at 650 Hz at a deviation of 50% of the maximum permissible frequency deviation and another at 2200 Hz at a deviation of 50% of the maximum permissible frequency deviation. The level of each of the two tones should be set to 50% of the generator's modulator input level specification. The deviation of the RF signal generator should be set to 100% of the maximum permissible frequency deviation. Adjust the level of the second RF signal generator to reduce the SINAD measurement back to 12 dB. Record the RF signal level. (c) Repeat step (b) with the frequency of the second RF signal generator set to the adjacent channel below the frequency of the first RF signal generator. (d) Calculate the ratios, in decibels (dB), of the undesired signal levels measured in steps (b) and (c) to the reference level obtained in step (a). The smaller of these ratios for the above and below channel undesired signals is the adjacent channel rejection. ---------------------------------------------------------------------- --- In Repeater-Builder@yahoogroups.com, "tahrens301" <tahr...@...> wrote: > > I have this lowband Micor receiver > that I want to test for adjacent channel > rejection. > > I have two calibrated signal generators > and a calibrated spectrum analyzer if > I need it. > > How can i measure the rejection of the > off channel signal? > > Thanks, > > Tim >
