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Lt. Commander

[import] Back to Back Repeater mode

>>Message imported from previous forum - Category:Trio Data Radios<<
User: joelw, originally posted: 2018-10-17 15:23:05 Id:48
This is a re-posting from the obsoleted (October 2018) "Schneider Electric Telemetry & SCADA" forum.

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**_alibaba:
Can i use 2 MR450 radio modems as a Back to Back Repeater?
- How i can configure the modems?
- How i should connect two radio serial ports to each other?
- My control Radio is ER450 half-duplex and Remote radio is MR450 ._**

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jdale:
If I understand properly, you have:

ER450 - MR450(repeater 1) - MR450(repeater 2) - MR450 (remote)

Is this a simplex (one frequency) or duplex system (two frequencies)?

You will need to go into the Stream Setup to translate streams through the repeaters. This can help ensure that a radio doesn't hear two identical messages from different sources.

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**_alibaba:
I want implement this mode similar to Point to Point via back to back repeater (Cross Over Cable connection) for ER450 with duplex system (two frequencies).
ER450(Control)MR450(Repeater1)------(Repeater2)MR450 MR450(Remote)_**

![]((see attachments below) yl/5tykgbdy602f.jpg "")

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jweder:
This system is somewhat different than one in which a single radio is acting as a Store & Forward repeater, which is what James was referring to in his earlier response. Yes it would be possible for ONE radio (ER450 or MR450) to act as a single-radio repeater, in which case the Stream Setup dialog would be edited to setup a range of SID's to be repeated. However, to address the case of a back to back repeater:

The two point to point radio links need to be on different channels, to avoid interfering with each other. (radio 1 at the back-to-back repeater is trying to receive a weak signal while radio 2 is transmitting) It is recommended that the frequency separation be approximately 5 MHz or more, and that the two antennas at the back-to-back repeater location be directly one above the other, spaced approximately 20 feet apart vertically. (at very least 12 feet) This ensures that the transmitting radio does not deafen the receiving radio.

Alternately a single omnidirectional antenna may be shared by both radios in the back-to-back repeater, by connecting them both to the antenna through a duplexer. This is a mechanical filter which can keep the two channels separate as long as they are about 5 MHz apart. An inexpensive band-reject duplexer such as our model 210095 will be fine if there are no other 450 MHz band transmitters at the same location. If other transmitters do share the location then a band pass duplexer such as our model 210129 should be used. This type can protect the receiving radio not only from the same system's transmitting radio, but also from all other nearby transmitters. The band-reject type can only protect against one transmitter.

The two radios in the back-to-back repeater will need to be physically connected by a 3 wire serial null (crossover) cable:
Radio 1 Radio 2
RxD --- TxD
TxD

Attached file: (editor/yl/5tykgbdy602f.jpg), Back to Back repeater with ER450.jpg File size: 183001