"Pulsing" Analog Audio?

[PeterGV]

I'm hoping somebody here can give me a clue about what might be causing this.

I've got a VHF XTS-5000 that *sometimes* has a "pulsing" sound when receiving analog audio. This pulsing seems to be exactly 2 times per second. It doesn't really sound like a ticking or a signal in the background. It's most obvious with static in the background, when it almost sounds like audio compression is rapidly being turned up and down ("pumping"?). The actual VOICE transmission doesn't "pulse" as much as the background noise level rises and falls in a periodic rhythm.

When it's doing this, I can put the radio in monitor mode (receiving nothing but static) and clearly hear the pulsing.

Note that it doesn't always exhibit this problem.

I've ruled out local interference as the source, because (a) I hear this same phenomenon even many miles from home, and (b) my XTS-2500 doesn't exhibit this symptom at all when connected to the same external antenna.

Any clues would be greatly appreciated.

Peter
K1PGV

[Josh]

It's probably the radio and due to old firmware. My XTS2500 with version R04.80.00 does it too. Time for an upgrade.

[PeterGV]

Good thought, but the firmware is R11.00.00, DSP R11.00.00

Thanks though,

Peter

[MT2000 man]

Hmmmm, may sound stupid and simple, but do you have your radio setup for priority scan ? That causes the pulse that you hear. I assume that you already checked that though . . .

[PeterGV]

Another good thought, but sadly no.

This radio doesn't have priority enabled, and there's no "little dot" after the "scanning Z"

(added later via edit) Interesting tidbit: You suggestion made me check, and it appears that I can make the pulsing stop if I take the radio out of scan mode. It resumes if I start scanning again. Hmmmm....

Peter

[txshooter]

Another good thought, but sadly no.

This radio doesn't have priority enabled, and there's no "little dot" after the "scanning Z"

Thanks,

Peter

Is the radio scanning while this is occuring? Does the radio do this with scan off?
Just because you don't see the dot does not mean it is not priority scan. The radio can be set with the priority channel slaved to the channel selector or the priority channel can be slaved to one channel and not selectable by the end user. I don't remember if the dot shows up in these circumstances or not, but it really does sound like the priority scan pulse.

[PeterGV]

Yeah... Thanks Txshooter... It DOESN'T do it with scanning disabled, which is something I just discovered tonight after reading MT2000Man's reply and playing with the radio some.

Me thinks I need to dig a big deeper and see if I've inadvertantly enabled a priority channel or something, now that I know what "priority scan" sounds like.

Many thanks to all of you... I'm off to investigate with CPS,

Peter

[MT2000 man]

Well, glad we could help I thought that sounded like a prioirty scan going on there.

I have all my radios set up where "B" it just scans, and "C" you can manually set up what channels to scan, and set up your priority as well (AKA Program Scan). At least now you found out what the issue was !