Any 900mhz users here? can u post your testimonials and experiences about this one… please… presently, we are using 5700Mhz, but we want to add for 900mhz considering the coverage.
please advise me if this will be a good decision or not. testimonials please.
I use all the bands but I have to because i have such a complex network with over 30 individual sites covering 15 diffarent towns. For my customers i try to put them on 5.7 if los if not i use 900. The majority of the sites have 5.7 and 900 colocated and running on the same cmm micro. I live in the mountains with tall pine trees and have had good luck with 900. The majority of the 900 is connectorized. Most of your cell and paging sites use vertical polerization that is why horizontal is a good choice. I use vertical because i have alot more antenna choices. I have not had any problems YET but i do good site planning and servays. I also use connectorized sm with a yagi antenna for the customers i can rotate the yagi for vertical or horizontal depending on the ap. I have had 900 couse problems on vhf equipment located on the same tower. the solution was to keep a minimum of ten feet seperation from the antennas. Good luck
Using 900Mhz going close to 7 Km’s through 30-50% deciduous trees (using Yagis for gain and avoiding the noise, but power output is legal). Barely clearing the fresnel zone in the middle and definately not at the ends for the first 1000 meters at least. Running Hardware Scheduling and 2X mode - a couple of lost sessions (registrations) but no re-reg’s. Link test shows 100% both ways and approx 3.3mbps/700kbps down/up. Only thing I’ve noticed is that if traffic is very high for and extended period of time the link may drop and register again - not sure what the problem is but the cuase is sustained high throughput like downloading the Fedora Core 4 CD’s sequentially. The user sees a drop in throughput on their transfers but the sessions doesn’t fail. Watch out for SCADA, CELL Towers and Police/Fire departments… ugly noise.
Over all I’m happy I chose Canopy for this paricular shot.
can post here a link of the Yagi Antennas you are using? please.
Thanks ahull,
anyway, can you give me an idea of the best antenna that would suit for a long range, say 38miles?
or…how far would the link will go if i use that antenna? whats the most effective antenna there?
I’m currently using the 13dBi model (HG913Y-NF) in two different 18 mile links.
When it comes to antennas I have found this: Higher gain antennas do nothing to improve distance or signal strength. When you think about it, this makes perfect sence: The EIRP (Equivalent <something> Radiated Power) is the same no matter what antenna you use – 4 watts. When using a higher gain antenna, you lower the power output in the SM (if you don’t, you’re violating FCC regs).
What the higher gain antennas do is elminate background noise, lowering jitter. With a higher gain, comes smaller beam width. This makes the area that possible sources of interference smaller.
For distance you need to do two things: keep the fresnel zone clear (and I mean really clear), and reduce background noise. At 38 miles you have around 120 dB of free space loss, considering that we are transmiting at 36 dB (36-120= -84) you are only going to have a -84 dB siganl strength at the other end (assuming ideal conditions!).
What’s the nominal sensitivity of the Canopy 900 units? -90 dB
What does this mean? That you only have 6 dB to play with. Start to factor in some fresenel obstructions and that 6 dB is going to dissapear fast. And that’s not giving yourself ANY fade margin.
Hope that gives you some information to go on. Moto may advertise 40 miles, but they forgot to mention the engineering requirements needed to make it fly. Too bad too, its easy for non-RF-heads to get over-confident in the ability of 900mHz Canopy when it comes to NLOS.
ahull wrote:
Higher gain antennas do nothing to improve distance or signal strength.
Not so, antenna gain ads to both ends of a link budget.
If I have a 17 dBi antenna looking at a 36 dB EIRP emitter and I replace it with a 14 dBi antenna my received signal will drop by 3 dB.
Even in the constraint of an absolute max of 36 dB EIRP, a higher gain antenna ADDS it's gain to the received signal. It is important to remember that antenna gain is added into link budget equations TWICE.
micers wrote: a(n) ... antenna ADDS it's gain to the received signal.
That's the detail I was forgetting. Thanks