Noise at console from DIU (white noise)

[Lotus54]

We are getting a fair amount of 'hiss' at the console (Zetron 4010).
Setup:
DIU to console- TRC, 4-wire (-10)

DIU to AstroTac 3000- AstroModem (-14dbm)

AstroTac to Quantar base stations- Astromodem (4-wire circuit) (-14dbm)

Levels are good, set the 'Silent Level' on all our DIU/Quantar setups and never seen one yet that needed anything but default. I'm going to double check this one, but will take quite a bit of time since the remote site is about 60 miles away.
The Zetron will mute idle and the noise goes away, but it is so aggressive it mutes when someone is pausing during transmission.

For those that don't know, the Quantar/AstroTac sends clear analog audio over the line during analog TX/RX with Astro signalling to pick channels and a fast train for the end.
During digital TX/RX it is all astro modem signalling, with no analog audio over the line.

Anyone has this setup with noise?
A new console would solve this, but not quite in the cards yet (hopefully fairly soon).

Mark

[RFguy]

Have you set up the console RX level for the proper "knee of compression" level?

[Lotus54]

Have you set up the console RX level for the proper "knee of compression" level?

Yes, but I'll double check that to make sure it is still correct with the change-over.

thanks
mark

[wa6ylb]

For those that don't know, the Quantar/AstroTac sends clear analog audio over the line during analog TX/RX with Astro signalling to pick channels and a fast train for the end.
During digital TX/RX it is all astro modem signalling, with no analog audio over the line.
Mark

Hmm. By time we bought our first DIU's, the astromodems were not available any more. So we had to go with V.24 daughter boards in the Quantars, and V.24 four wire external lease line modems from the Quantar to DIU connections. We ran four wire RX&TX lines for analog audio, and 4 wire (two pair) for the modems. The modems are always on line to each other. Never any retraining of the V.24 circuit.
Saying all of that, we have 4 wire remotes on the DIU and don't hear this noise. The MCC5500 console also connects to the DIU, but no hiss is detected there either.
B.

[RKG]

Have you set up the console RX level for the proper "knee of compression" level?

Yes, but I'll double check that to make sure it is still correct with the change-over.

thanks
mark

Also take a look at the VOX level on the Zetron channel card.