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The problem with SNR for alignment
purposes is that you are dealing with a variable in noise, with rssi you work
with fixed numbers. I’m not dissing SNR, it is extremely important,
But for example, in order to trouble shoot a link … let say I install a
Link and Im seeing a a SNR of 6 on this link,how the heck can I determine if
the antenna is miss aligned or the noise floor is very high ??? Gino A. Villarini From:
[EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Patrick Leary Right, but the LED bar on the CPE can be used to do that. I mean, isn't
SNR more complete than just RSSI, meaning if your SNR is good than the RSSI is
by default good. Anyway, I have never heard of any moderately experienced VL
user say the units did not convey enough info to easily establish a link and
understand the quality of the connection. Consider that with the CPE VL radio
the LEDs will show: WLAN link light- ·
Solid Green – Unit is
associated with an AU, no wireless link activity ·
Blinking Green – Data
received or transmitted on the wireless link, blinking rate is proportional to
wireless traffic rate ·
Off – Wireless link is
disabled Status light – ·
Solid Green – Power is
available and self-test passed ·
Blinking Amber – Testing
(not ready for operation) ·
Red – Self-test failed
– fatal error Ethernet light – ·
Solid Green – Ethernet link
between the indoor and outdoor units is detected, no activity ·
Blinking Green – Ethernet
connectivity is OK, with traffic on the port. Blinking rate proportional to
traffic rate ·
Red – No Ethernet
connectivity between the indoor and outdoor units SNR bar – ·
Red LED: Signal is too low
(SNR<4 dB) ·
Orange LED: Signal is too high
(SNR > 50 dB) ·
8 green LEDs: Quality of the
received signal (green LEDs translate per below) LED 1 (red) is On - Signal is too low (SNR < 4 dB) LED 2 (green) is On - SNR > 4 dB LEDs 2 to 3 (green) are On - SNR > 8 dB LEDs 2 to 4 (green) are On - SNR > 13 dB LEDs 2 to 5 (green) are On - SNR > 19 dB LEDs 2 to 6 (green) are On - SNR > 26 dB LEDs 2 to 7 (green) are On - SNR > 31 dB LEDs 2 to 8 (green) are On - SNR > 38 dB LEDs 2 to 9 (green) are On - SNR > 44 dB LEDs 2 to 9 (green) and 10 (orange) are On Signal is
too high (SNR > 50 dB) Mod level : Sensitivity : Min. SNR (this chart for
20MHz channel) 1 : -89 dBm : 6 dB 2 : -88 dBm : 7 dB 3 : -86 dBm : 9 dB 4 : -84 dBm : 11 dB 5 : -81 dBm : 14 dB 6 : -77 dBm : 18 dB 7 : -73 dBm : 22 dB 8 : -71 dBm : 23 dB Patrick Leary AVP WISP Markets Alvarion, Inc. o: 650.314.2628 c: 760.580.0080 Vonage: 650.641.1243 -----Original Message----- Patrick, Rssi is very important to determine if a link is properly aligned and
its achieving its link budget. Altough we don’t use alvarion(yet), we are currently researching
backhaul options and the way we comission ptp links here is that we run the
calcs on radio mobile and spreedsheet to determine the link budget in advance
to implementation. Snr won’t help much there... Gino -----Original Message----- From: "Patrick
Leary"<[EMAIL PROTECTED]> Sent: 9/24/06 11:32:47 AM To: " Subject: RE: [WISPA] vendor specs Brad, Software controlled dual polarity might be nice. Not
sure why you consistently harp on us though since no one else has
it either other than your longtime preferred vendor. I am not as convinced about your complaint about
RSSI. Is it just used to RSSI like being used to feet in stead of meters.
But also, isn't RSSI less sophisticated and a less useful number than SNR
since it is only an indication of receive signal without discounting noise?
SNR provides a more accurate representation of wanted signal since
it discounts for unwanted noise. Not sure of your complaint about the RJ45. No one
else remarks about it and we don't have issues with water intrusion. In
other words, it works well. If the opening was enlarged you increase the
potential for water intrusion. Following the color code? Yes, as an old cabling
guy, I would agree. But I am pleased to note that one is really running out
of things to harp about when one continually highlights this a major
deficiency. So now that I have responded here to your public
mail, will you please admit that even if the VL came to life and saved
your kid from a flood you complain that it was not fast enough and that it
ripped the kid's clothes. I wish some day you'd accept that your
customer chose VL and you should take the opportunity to learn about it
instead of still trying to make it fail so you can get them to switch
to Trango. Even the best radios will have room for improvement and every
decent brand should have something special that differentiates it. You
work so hard to find fault you miss opportunities to become proficient in
more than one brand. So accept our invitations to allow engineer
visits and accept our invitations to be trained. Know what I mean? Patrick Leary AVP WISP Markets Alvarion, Inc. o: 650.314.2628 c: 760.580.0080 Vonage: 650.641.1243
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