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Hello,
I am working with a Wireless Public Address system which transmits a Pilot Tone which is similar to CTCSS except it is Super-Audible vs Sub-Audible @32KHz.
My objective is measure both the exact frequency and deviation of this tone. The TX frequency is 507.500MHz @10dBm for wireless Mic’s.
Attached is the TX spectrum with the Pilot Tone.
Also attached is the Zero Span mode.I think the FM Deviation is +/-48KHz which seems high compared to Sub-Audible tones used for Two-Way Radio equipment.
The Equipment Audio specs also call for +/-48KHz Max. Can the Pilot Tone and normal audio (20-20KHz) co-exist at the same time?
I know the Pilot Tone frequency is close to 32.768KHz but I want to measure it exactly.
Thanks,
Jay Zebryk
Jay@Zebryk.comJay,
Our Audio Demod tool in Spike would be able to give you the exact frequency of the audio pilot tone, but unfortunately it clamps to 20 kHz. In normal swept mode your accuracy will be limited to your RBW. Marker peak, delta, next peak would give you the audio frequency +/- your RBW. An RBW of 1 Hz would give you a 1 Hz accuracy. If this is not accurate enough, the next step would be to either put in a request for us to increase the maximum audio frequency in the Audio Demod mode, or use the API and do the FM demod yourself.
The peak deviation can be viewed in zero span mode FM, as you did. Measuring a local max, then a local min, with markers, should give you a peak-to-peak deviation.
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