Duplicate repeater frequencies?

[sdnative]

I recently bought software to program my radio, so I decided to program all of the San Diego, Riverside, Imperial, and San Bernadino county open repeaters (so far ), and setup some pretty trick profiles (using hypermemories and such). Stuff that would be near impossible to do without some form of management software.

Anyway, I was scanning through all of the memories the other day, and I was getting a very strong signal on some palm springs and san bernadino repeaters. Wow! I was impressed. Come to find out, there are several groups of repeaters in these areas that use the same frequency. I imagine it is possible, depending on where you are, to be in range of all of them at once. Tranmitting is not an issue, since the PL is different, but receiving could get interesting.

One example is 147.030, but there are others.

Who coordinates the repeater frequencies anyway, and given the large range of the 2m band, why are these repeaters given the same frequency?

[taugust]

I believe the organization that coordinates these frequencies is TASMA Two meter Area Spetrum Management Assn. at http://www.tasma.org/. Their website has a color coded list (by county) of all the repeaters in So Cal, in frequency order. Since there are a limited number of standard repeater pairs, this group evidently coordinates everything, probably based on repeater output power, location and PL tone. For various reasons, unknown to me, repeaters will sometimes swap input and output frequencies. They can do this, I believe, because they are licensed for the repeater pair. For instance, Keller Peak (where we hold the OAUSA net), recently swapped input/output freqs. The TASMA site still contains the old frequency and offset direction. Hope this helps.

[Frogeye]

Eric, I've seen dup freqs. but with different PL Tones.

[sdnative]

Eric, I've seen dup freqs. but with different PL Tones.

Yes, these have different PL tones, so transmitting is not a problem. It would be possible to receive transmissions from multiple sources though.

[OLLIE]

Being located as close to the border as I am, the 147.030 frequency is a constant problem for me. There is a group south of the border that uses the same frequency for their repeater and I constantly get noise and chatter from them. There's also a repeater in the Orange County, Anahiem, and LA area on that same frequency that I pick up when scanning while traveling up there too. The 146.640 freq has some of the same issues.

[hmfigueroa]

The various frequency management organizations do there best to eliminate co-channel interference. It is very difficult especially in heavily populated areas with tall mountains.

There are ways of minimizing co-channel interference that include using directional antennas, terrain features and technical standards to ensure top notch communications systems.