To back up my claims of low noise floor, here's 5 minutes of airtime sampled from a 900MHz antenna @ Haystack, aimed roughly at Everett (287 degrees): I don't use this system anymore, so I'm making it available for HamWAN experimentation for the next few weeks/months. To use it: Modem: Rocket M900 / M9, or compatible, dual-polarity MIMO. Antenna: https://www.ui.com/airmax/airmax-yagi-antenna/ SSID: HamWAN Frequency: 917MHz Bandwidth: 5MHz Mode: AirMAX TDMA Security: None IP: DHCP Please let me know if you're attempting to connect, regardless of success or failure, as both results are useful. --Bart On 5/23/2019 10:16 AM, Bart Kus wrote:
Another thing to mention about 900MHz usage is that it's very close to really powerful paging / cell systems. We had to use an 8-cavity super-narrow bandpass filter to make the 900MHz installation @ Gold Mtn work. The initial deploy didn't use said filter, and the adjacent QRM was so bad that I couldn't even connect to the AP from the base of the tower! I have several more filters in stock to support any possible future site deployments.
In my surveys, I haven't observed the high in-band noise floor that others are reporting.
Due to the lower gain and directivity of 900MHz antennas, the signal levels are low, and higher power would be useful. Sadly, 900MHz bidirectional amplifiers are still prohibitively expensive. If I recall correctly, the math models I did for 900MHz mobile coverage required something like 500W peak amplifier performance to get decent data rates.
Sad to hear about the EOL of the 9HPn. :( In light of that news, it probably makes sense to re-work that system with available gear, such as UBNT.
--Bart
On 5/23/2019 10:03 AM, Bryan Fields wrote:
On 5/23/19 12:57 PM, Steve wrote:
The 900 MHz noise floor is pretty bad around the populated areas. Lots of utility's use it now.
The narrower the better. If it's just a ptp use, a M2 yagi will help.
Also, there are radios from the mid 2000's mabe by alvarion: https://www.ebay.com/itm/162895142474 They are a 2 mhz channel and will do about 1.5 Mbit/s and 550 packets/sec. It's not a lot but if it's behind trees, it's just fine for a link or a few phones.
73's
_______________________________________________ PSDR mailing list PSDR@hamwan.org http://mail.hamwan.net/mailman/listinfo/psdr
