[Imported] Growing an existing Licensed radio system

[sbeadle]

>>Message imported from previous forum - Category:Trio Data Radios<<
User: joelw, originally posted: 2018-10-17 21:33:18 Id:111
This is a re-posting from the obsoleted (October 2018) "Schneider Electric Telemetry & SCADA" forum.

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**_jweder:
You may have an existing system with a radio model that is not compatible with Trio radios. Perhaps your older system is becoming unreliable, or as more sites are added the system's polling cycle time is growing too long. The most significant issue is the need to add new radios (eg Trio QR450) which may be incompatible with the existing products, while avoiding any increase in the polling cycle time. (and eventually reducing it) Here are a few possibilities:_**

**Grow with a single radio frequency**:
If you have both existing radios and Trio radios on the same frequency, and the master radio on one network transmits while the master on the other network is trying to receive, the 5 or 10 watt transmitted signal could completely deafen (or even damage) the radio trying to receive. This might be possible to get working under two conditions:
1) Your SCADA Host device or computer is able to talk on two communication ports (existing on one and Trio on the other) and MUST be configured to only use one of the two ports at any time. This way if one Master radio is transmitting it doesn't much matter if it interferes with the other, as that other radio system is currently sitting idle. Note that this will ONLY work in a poll/response scenario - If a remote site is able to generate traffic on its own (Unsolicited messaging) then interference is impossible to control.
2) Each Master site radio will need its own antenna, and there will have to be significant vertical separation between them (with little or NO horizontal separation). 10 or 12 feet should suffice. This is only to avoid having the transmitting radio physically damage the other radio's receiver by sending its very strong signal on the same channel the other radio is listening to.

**NOTE**: In this scenario the total polling cycle time will get longer as you add more radios. Maybe not a good solution if you need to speed things up.

**Acquire a second radio frequency and set up a parallel system**:
In order to avoid adding to the polling cycle time you will need to add the new system in parallel with the old one.As one Master radio may be transmitting while the other is receiving, there are a couple of conditions to avoid interference problems:
1) Both systems will operate independently on separate communication ports. (serial and/or ethernet)
2) A second frequency must be acquired, at least 5 MHz away from the original channel.
3) The new antenna needs to be about 20 feet above or below the original one, with little or no horizontal separation.

**Acquire a second radio frequency but keep a single Master site antenna:**
If it is difficult or expensive to add a second antenna to the Master site tower or mast, it is possible to have both systems share a single antenna. This is done in the following manner:
1) As above, acquire a second frequency at least 5 MHz away from the first.
2) Purchase a duplexer (offered by Trio), which is a mechanical filter that keeps each radio's transmit signal out of the other radio's receiver. (must specify both frequencies when ordering the duplexer)
3) Connect both radios to the duplexer, then the common port to the antenna.

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Joel A. Weder
SCADA & Telemetry Solutions Specialist
Schneider Electric