Linking Repeaters without using IP Multisite

[ayman1986]

Hi all
I have two Hytera RD985s repeaters and i want to connect both sites together
I have tried to revers frequencies but no way

 

[RFI-EMI-GUY]

Why would you not use IP Multisite? What you have tried will never work for a buch of reasons including incompatibility of up and down link data schemes. I am assuming you are not in US due to the frequencies you are using. I would suggest using a UHF IP backhaul product in the 400 or 900 MHz range. Also if you have overlap in coverage, the VHF frequency pairs you have will need to be different.

 

[ayman1986]

That's right I'm in Meddle East , I'm using Hytera RD985s VHF repeater . the distance between sites is 90 KM across air , i'm using Tx= 141 and Rx= 146 . I can use Ubiquity airFiber radios to make LAN between two sites but that expensive

 

[RFI-EMI-GUY]

You dont need much bandwidth for this so you could use other IP radios in Narrow band, UHF.

 

[ayman1986]

Can u tell me more about ovelapping and how frequencies should be written for my topology

 

[RFI-EMI-GUY]

Can u tell me more about ovelapping and how frequencies should be written for my topology

Assuming your sites are 55 KM from each other and there are no locations between when both repeaters can be heard at once you could run both repeaters on same pairs, say 141.000 and 146.000 MHz.

But more likely, if they overlap, which could occur if a vehicle is on terrain favorible to both repeaters, or if tropo ducting takes place, which can be frequent, then the pair for repeater # 1 should be 141.000 and 146.000 MHz while repeater #2 should be 141.025 and 146.025 MHz or other pair sufficiently separated channel wise from #1. With IP Multisite and appropriate radio firmware, the radios can be programmed to automatically roam from Repeater #1 to # 2 and vice versa.

 

[ayman1986]

have u ever tried to work on Hytera RD98s VHF repeater ?
i can send codeplug of my repeater to see if there's some modifications

 

[RFI-EMI-GUY]

have u ever tried to work on Hytera RD98s VHF repeater ?
i can send codeplug of my repeater to see if there's some modifications

I would not be much help there.

 

[speedway_navigator]

Hytera does have a cable (I think it's a PC-49) that goes from the RD985 to a mobile like the MD985 so you can use a separate freq to link the sites. At 90 km you are looking at 115 dB path loss at 140 MHz, that shouldn't be a major hurdle with a 40W / 46 dBm mobile and yagis.

I'm not sure what the path would look like from a Fresnel zone or earth curvature issue, that's beyond my expertise.

 

[ayman1986]

i've tried using that cable but not success
it might be i miss configured PINS ,so when i connect cable between RD985s and MD785i a continous none stop signal goes from MD785i to RD985s .

 

[Expat2017]

Does this help?