USCI Question

[KI4M]

I have acquired a used USCI with TRN7349 cards. I am currently planning a 2 site ham simulcast and was wondering what the significant difference in this card is v/s the QTN6066D card used in a CSCI is? I am not going to be running a PL on the base station transmitters so PL generation isn't a concern. All I am concerned with is the audio and PTT functions in my application. I know these generate low speed data and I would need to have that muted as much as possible. Has anyone used one of these USCI cards in a CSCI with any success when you didn't need PL generation? Just trying to avoid having to buy a CSCI card if I can use the USCI cards I have. I have 5 USCI cards in this cage so if anyone needs one and has some CSCI cards they would like to trade that might be an option also.

Shane KI4M

[Bill_G]

Here are two Batboard threads discussing USCI and CSCI -

Aug 2005
Apr 2009

[KI4M]

Thanks for the links. I do have the Manual referenced in the above article. I have found two CSCI modules this week and will be using those. Looks like a USCI can be used as long as you turn the data down on the card and if you do not need TX PL. I did find it interesting that there is a connect tone of 97.3 Hz which is awfully close to a PL tone of 97.4 Hz. I bet you could use that as a TX tone and most subscribers wouldn't notice the difference unless they got into fringe coverage with signals in the < -110 dBm range. Would be fun to try but for this project that isn't necessary. Thanks to those who replied privately as well.

[d119]

Connect tone is subscriber generated though.

Keep us posted on this project - I'm very interested. Where did you find a CSCI shelf & cards? Keep in mind you only need one CSCI card per simulcast channel, not one per site.

[desperado]

As far as the PL comments. I installed and manage a Harris / Spectracom based 5 site 2 channel simulcast system for a county in Ohio. The Spectracom GPS and a module attached to it generate the PL for the system. The PLs that it generates are NOT right on. They range from .1 to .3 off the standard PL frequency and work fine. I would say it's a safe bet that if you were to generate at 97.3 that a radio listening for 97.4 would have no issue hearing it. I am going to assume that you are familiar with configuring simulcast and what that entails. Timing while important, is not near as important as the audio levels matching exactly and the PL levels and phases matching exactly. The PL getting out of phase or level differences will cause growling RX during no transmitted audio and receiver drop out due to the low level that the PL already is and phase cancellation lowering it even more.

[KI4M]

Connect tone is subscriber generated though.

Keep us posted on this project - I'm very interested. Where did you find a CSCI shelf & cards? Keep in mind you only need one CSCI card per simulcast channel, not one per site.

Interesting enough I didn't think about that being subscriber generated. I found a guy who had two CSCI cards and some DSM II cards. He had two. I bought my USCI shelf and 5 cards off a popular auction site. I got a good deal on all items from the different vendors. The reason I went for two cards is one for the system and one for a spare. As hard as these things are to find when he said he had two I grabbed them both.