Hi all, i'm quite newbie to radio data trasmission.
I need to setup a cheap link between a car and a base station, link one direction, from car to base station.
Car will continuosly feed the RS-232 and base statio will show the data coming from the car, speed is not an issue, with 2400/4800 bps i'm fine, more of course is better.
I've fount quite cheap motorola modems VRM850 so i'm asking you if with 2 of them, one as the base station and one in the car i can do this work.
where is possible to find a manual for this modems ? On the motorola website i hanven't found anything.
Best Regards.
Point to Point Data link with VRM850
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Re: Point to Point Data link with VRM850
Someone correct me if I'm wrong on this, but I don't think it can work that way.
The VRM850 was designed to work with an RNC attached to DBS (Data Base Station) equipment. The RNC essentially maintains an authorization database of which VRM's are permitted to access the system, and also handles doling out the data to various DBS's depending on RSSI, etc. in addition to providing the "gateway" to the CEN (Customer Enterprise Network) via RS-232 or IP.
In my years of working on VRM 600/650/850 units, I've never seen anything in WinRSS to suggest that point-to-point is even an option. I know for a fact that it cannot work on the 800MHz VRM's, as these are locked to 806-821(ish)MHz TX, 850-868MHz RX. There's no way to do simplex with them. Same deal for the 900MHz VRM's. As for the UHF VRM's, I've only ever seen one UHF system so I don't know if they can do it or not, but I would assume they can't. This system, as a whole (including RNC, DBS, VRM's, etc.) was marketed as "DataTAC" was designed for one purpose, and radio-to-radio wasn't it. The replacement for it is HPD (High Performance Data). You probably already knew all of this if you're in possession of a VRM.
Maximum speed on these things is 19.2kbps, but at 5.3kHz deviation.
The VRM850 was designed to work with an RNC attached to DBS (Data Base Station) equipment. The RNC essentially maintains an authorization database of which VRM's are permitted to access the system, and also handles doling out the data to various DBS's depending on RSSI, etc. in addition to providing the "gateway" to the CEN (Customer Enterprise Network) via RS-232 or IP.
In my years of working on VRM 600/650/850 units, I've never seen anything in WinRSS to suggest that point-to-point is even an option. I know for a fact that it cannot work on the 800MHz VRM's, as these are locked to 806-821(ish)MHz TX, 850-868MHz RX. There's no way to do simplex with them. Same deal for the 900MHz VRM's. As for the UHF VRM's, I've only ever seen one UHF system so I don't know if they can do it or not, but I would assume they can't. This system, as a whole (including RNC, DBS, VRM's, etc.) was marketed as "DataTAC" was designed for one purpose, and radio-to-radio wasn't it. The replacement for it is HPD (High Performance Data). You probably already knew all of this if you're in possession of a VRM.
Maximum speed on these things is 19.2kbps, but at 5.3kHz deviation.
Re: Point to Point Data link with VRM850
Yep, your workds are a confirmation of my suspects, then what options i have to setup such link ? Mi minimum rquirements are:
-Speed min 4800
-Power 15W min
-Band not in the 400 Mhz
-One way only
-Speed min 4800
-Power 15W min
-Band not in the 400 Mhz
-One way only
Re: Point to Point Data link with VRM850
Look at the products made by Microwave Data Systems (MDS), now a subsidiary of GE I believe.
They'll do whatcha want.
They'll do whatcha want.
Re: Point to Point Data link with VRM850
Had a look to them but they are quite off budget....
Re: Point to Point Data link with VRM850
There are a number of other mfgs out there including MDS as d119 mentioned. Dataradio, now CalAmp, has many products that are out of the box ptp capable in a number of bands with a low learning curve. Won't meet your min power spec though. Esteem is another, and they do have high power product.