900 Mhz radios

rlloyd [ 2006/10/05 19:24 ] :

The main advantage of the 900MHz band is the signal propagation compare to higher frequencies like 2.4 and 5.8 GHz. Some manufacturers advertise their product as NLOS (near/non line of sight) but you have to keep in mind that in the field, the NLOS is not achievable in all situations.

For my project, I planned to use Airspan WiPLL 900.

Here is other suppliers of 900MHz products:

- Motorola Canopy

- Trango Broadband

- Osbridge

Maxim

Maxim Chartrand hath wroth:

Agreed. NLOS is (in my opinion) close to science fiction. At best, it can be made to work, but will not stay working as things move around. The big advantage of 900MHz is that it will penetrate a forest. I've had quite a bit of experience with Metricom/Ricochet

900MHz radios in the distant past. Pure magic the way it goes through the trees. The problem is that the 900MHz allocation is only 26MHz wide, while the 2.4GHz allocation is 83.5MHz. The result is that the maximum speeds on 900MHz are seriously limited. In addition, much of the hardware are FHSS (frequency hopping spread spectrum) instead of the more common DSSS (direct sequence spread spectrum). FHSS is inherently slower than DSSS.

From my bookmark pile.

Trango:

Avalan: Waverider: Freewave: Rotomola:

FWIW, I see Metrocom 900Mhz radios at electronics flea markets from time to time. Price around $25 to $40. I'm not sure if they can talk to each other, or need the unit on the power pole.

snipped-for-privacy@sushi.com hath wroth:

Metricom/Ricochet modems come in a variety of packages and models. The system is still in use in Denver and San Diego and owned by Aerie, YDI, Terabeam, and I guess now Proxim. I still have a small pile of radios. There's also the Utilicom(?) products, which were sold to Shlumberger long ago.

Most (not all) models will talk to each other or you can build a network using star mode (STRIP). Of course there are bugs. As I recall, you have to set ATS340=00 (???) or the point to point performance sucks. Some models (forgot which ones) insist on connecting to the non-existing network. In general, the ones with xxxx-xxxx serial numbers work. Longer serial numbers don't. The Windoze dialer doesn't like the hyphen in the dialing string. Etc, etc, etc. Should keep you entertained. |

| | | | | Phase II antenna adapter: |

What I find surplus are the pole mounted units minus antennas. Either the antennas have use in another system, or the units are duds and the antennas pulled for spares.

snipped-for-privacy@sushi.com hath wroth:

The pole top repeaters won't do you any good without the magic AT incantations necessary to configure them. What you want are the older Phase II client radios, or the Utilinet radios.

will talk to each other quite nicely with about 25Kbits/sec IP thruput using modem emulation, and about 50Kbits/sec in star mode.

Modem commands: |

Nothing useful on eBay at this time, but they appear erratically.