Batboard

We have a 4 channel conventional UHF Astro system, each chanel has a Quantar repeater with a DIU connected. the system is connected to 2 antennas via a TX/RX combiner/Multicoupler.
we are currently having a problem when some of portables transmit on secure. When they transmit the signal is all garbbled, sometimes it clears up and sometims it does not.
the problem does not seem to affect the mobile units.

This problem seemed to surface after we changed our encryption code.

Does it matter if it the portable is transmitting secure or not when garbled?

tpg

Is it always the same portables, and/or can you track it to any particular Quantar?




Jack

i would also try to isolate the portables that are garbling... not only to a particular repeater, but for the purposes of "benching" those radios... and checking their alignment, etc.

i don't think you have an infrastructure problem tho...

i think it's your portables tuning.



doug

the problem only happens when the portables are transmitting in secure mode. It also seems to be select units it happens on multiple channels...

We are working on tracking which units are having the problem...

Does the Auto tune software from genral dynamics work well..??
I am looking into purchasing it.

Just some corrections to the original post. I'm a user on the system. I have observed mobiles have the same problems, and on different channels.Portables seem to have the problem more. The Secure modules in the DIU were zeroed, and the key reloaded.The problem is still there. All the channels have the same key. As stated above, the problem was noticed after the original key was replaced.

Could the new key be the incorrect algorithm?

I have seen similar symptoms when one radio was programmed with DES-XL and one with DES-OFB.

All the radios and DIU were programed with the same key from the same KVL.The problem is only heard sometimes, and from various units, portable and mobile.Re key is a last option as there's almost 300 radios.

I know that this may be a silly question, but is multikey involved? If there is an indexing issue here, some of those radios may simply be using the wrong key. Especially if there are different individuals involved in rekeying and or a training issue. Don't rule out human error and other simple but capricious issues...


Jatla.

No multi key involved. Its like it takes a second for the DIU to decode.I'm leaning towrds it being a signal problem. It happens more on portable than mobile. When a mobile does do it, its usually on the edge of town. We're installing remote receivers soon, so we'll see. Thanks for your input
Chris

I'd check the input freq, and see if someone new it transmitting on it (also check the FCC site). This happened to us, and it screwed with us for awhile. This one PD was also .25 off from our channel.

try adding you rremote rx sites first

What test gear do you have access to?

We have a R2625 digital and an older 2600 non digital service monitors. We're having our tower company come in and check all the antennas and cables.