Re: [amsat-bb] EO-80 FM Transponder Tested (noise floor?)
I also am a proponent ot using 2m for weak downlinks because of the 9 dB advantage. But it has been pointed out to me that there is a higher background noise component that needs to be considered. I have not done this. My assumption is that the noise floor at 2m is maybe about 3 dB worse than at 70cm?
So 2m still wins, but I'm not sure of what the real noise floor is.
Bob, WB4aPR
-----Original Message----- From: AMSAT-BB [mailto:[email protected]] On Behalf Of Zach Leffke Sent: Wednesday, June 17, 2015 11:23 AM To: [email protected] Subject: Re: [amsat-bb] EO-80 FM Transponder Tested
Paul beat me to the punch as I was typing up my response, but I'm sending it anyway:
Path Loss. -> function of lambda (wavelength) squared. So all other things being equal (antenna gains, power levels, range, etc.), you can look at the power ratio of the two.
Rough calculation (going from 2m to 70cm): 10log[(0.70/2)^2] = -9.1 dB OR Rough calculation (going from 70cm to 2m): 10log[(2/0.7)^2] = +9.1 dB
The thing to watch out for is antenna gains on the ground. The arrow for example has more gain on 70cm (7el) than it does on 2m (3el). So while 2m has a 9-ish dB improvement over 70cm in terms of path loss, the receiver may not see the full 9dB because of the difference in gains on the antenna between the two bands.
Again VERY rough approximation (for demonstration purposes only): 3el yagi -> call it 7.5 ish dB of gain 7el yagi -> call it 11.5 ish dB of gain so, about 4 dB of LOST gain (going from 70cm to 2m using the arrow example).
So net gain going from 70cm to 2m (all other things equal except the gains on the arrow antenna) 9dB - 4dB = 5dB
so your typo was actually fairly close :-) for those planning to use their existing setup for the new birds.
-Zach, KJ4QLP
On 6/17/2015 10:43 AM, Andrew Koenig wrote:
*9dB (typo)
On Wed, Jun 17, 2015 at 9:42 AM, Andrew Koenig [email protected] wrote:
Can you explain the 6dB advantage 2m has over 70cm? I've seen it here on the amsat-bb, and in the mesh realm when comparing 2.4GHz and 5.8GHz WiFi gear, but it still hasn't "clicked."
73 de KE5GDB
On Tue, Jun 16, 2015 at 6:56 PM, Paul Stoetzer [email protected] wrote:
Nick,
It should be even stronger than AO-27's 500 mW, AO-27 had a 70cm downlink, the EO-80 downlink is on 2 meters, so EO-80's signal should be up to 9 dB stronger than AO-27 (12 dB stronger if they run it at 1 watt).
73,
Paul, N8HM
On Tue, Jun 16, 2015 at 7:49 PM, Nicholas Mahr [email protected] wrote:
Thats very good news, Hopefully the two get activated before field
day?
Im
most looking forward to EO-80, It should be like AO-27 with 500Mw or
1W.
Good to know both are working well and wish a long life to them.
73 KE8AKW _______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring
membership.
Opinions expressed
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of AMSAT-NA.
Not an AMSAT-NA member? Join now to support the amateur satellite
program!
Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring
membership.
Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite
program!
Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
-- Andrew Koenig
_______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
That is definitely true. I have terrible noise in certain directions here in southwest Washington, DC (especially at night - the lighting on the north fence of my apartment building puts out a hash that completely wipes out 2m, but is OK on 70cm). The noise level doesn't affect FM as much, though.
73,
Paul, N8HM
On Wed, Jun 17, 2015 at 12:26 PM, Robert Bruninga [email protected] wrote:
I also am a proponent ot using 2m for weak downlinks because of the 9 dB advantage. But it has been pointed out to me that there is a higher background noise component that needs to be considered. I have not done this. My assumption is that the noise floor at 2m is maybe about 3 dB worse than at 70cm?
So 2m still wins, but I'm not sure of what the real noise floor is.
Bob, WB4aPR
-----Original Message----- From: AMSAT-BB [mailto:[email protected]] On Behalf Of Zach Leffke Sent: Wednesday, June 17, 2015 11:23 AM To: [email protected] Subject: Re: [amsat-bb] EO-80 FM Transponder Tested
Paul beat me to the punch as I was typing up my response, but I'm sending it anyway:
Path Loss. -> function of lambda (wavelength) squared. So all other things being equal (antenna gains, power levels, range, etc.), you can look at the power ratio of the two.
Rough calculation (going from 2m to 70cm): 10log[(0.70/2)^2] = -9.1 dB OR Rough calculation (going from 70cm to 2m): 10log[(2/0.7)^2] = +9.1 dB
The thing to watch out for is antenna gains on the ground. The arrow for example has more gain on 70cm (7el) than it does on 2m (3el). So while 2m has a 9-ish dB improvement over 70cm in terms of path loss, the receiver may not see the full 9dB because of the difference in gains on the antenna between the two bands.
Again VERY rough approximation (for demonstration purposes only): 3el yagi -> call it 7.5 ish dB of gain 7el yagi -> call it 11.5 ish dB of gain so, about 4 dB of LOST gain (going from 70cm to 2m using the arrow example).
So net gain going from 70cm to 2m (all other things equal except the gains on the arrow antenna) 9dB - 4dB = 5dB
so your typo was actually fairly close :-) for those planning to use their existing setup for the new birds.
-Zach, KJ4QLP
On 6/17/2015 10:43 AM, Andrew Koenig wrote:
*9dB (typo)
On Wed, Jun 17, 2015 at 9:42 AM, Andrew Koenig [email protected] wrote:
Can you explain the 6dB advantage 2m has over 70cm? I've seen it here on the amsat-bb, and in the mesh realm when comparing 2.4GHz and 5.8GHz WiFi gear, but it still hasn't "clicked."
73 de KE5GDB
On Tue, Jun 16, 2015 at 6:56 PM, Paul Stoetzer [email protected] wrote:
Nick,
It should be even stronger than AO-27's 500 mW, AO-27 had a 70cm downlink, the EO-80 downlink is on 2 meters, so EO-80's signal should be up to 9 dB stronger than AO-27 (12 dB stronger if they run it at 1 watt).
73,
Paul, N8HM
On Tue, Jun 16, 2015 at 7:49 PM, Nicholas Mahr [email protected] wrote:
Thats very good news, Hopefully the two get activated before field
day?
Im
most looking forward to EO-80, It should be like AO-27 with 500Mw or
1W.
Good to know both are working well and wish a long life to them.
73 KE8AKW _______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring
membership.
Opinions expressed
are solely those of the author, and do not reflect the official views
of AMSAT-NA.
Not an AMSAT-NA member? Join now to support the amateur satellite
program!
Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring
membership.
Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite
program!
Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
-- Andrew Koenig
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb _______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
why can we not get an old skool mode "A" back?
Joe WB9SBD Sig The Original Rolling Ball Clock Idle Tyme Idle-Tyme.com http://www.idle-tyme.com On 6/17/2015 11:26 AM, Robert Bruninga wrote:
I also am a proponent ot using 2m for weak downlinks because of the 9 dB advantage. But it has been pointed out to me that there is a higher background noise component that needs to be considered. I have not done this. My assumption is that the noise floor at 2m is maybe about 3 dB worse than at 70cm?
So 2m still wins, but I'm not sure of what the real noise floor is.
Bob, WB4aPR
-----Original Message----- From: AMSAT-BB [mailto:[email protected]] On Behalf Of Zach Leffke Sent: Wednesday, June 17, 2015 11:23 AM To: [email protected] Subject: Re: [amsat-bb] EO-80 FM Transponder Tested
Paul beat me to the punch as I was typing up my response, but I'm sending it anyway:
Path Loss. -> function of lambda (wavelength) squared. So all other things being equal (antenna gains, power levels, range, etc.), you can look at the power ratio of the two.
Rough calculation (going from 2m to 70cm): 10log[(0.70/2)^2] = -9.1 dB OR Rough calculation (going from 70cm to 2m): 10log[(2/0.7)^2] = +9.1 dB
The thing to watch out for is antenna gains on the ground. The arrow for example has more gain on 70cm (7el) than it does on 2m (3el). So while 2m has a 9-ish dB improvement over 70cm in terms of path loss, the receiver may not see the full 9dB because of the difference in gains on the antenna between the two bands.
Again VERY rough approximation (for demonstration purposes only): 3el yagi -> call it 7.5 ish dB of gain 7el yagi -> call it 11.5 ish dB of gain so, about 4 dB of LOST gain (going from 70cm to 2m using the arrow example).
So net gain going from 70cm to 2m (all other things equal except the gains on the arrow antenna) 9dB - 4dB = 5dB
so your typo was actually fairly close :-) for those planning to use their existing setup for the new birds.
-Zach, KJ4QLP
On 6/17/2015 10:43 AM, Andrew Koenig wrote:
*9dB (typo)
On Wed, Jun 17, 2015 at 9:42 AM, Andrew Koenig [email protected] wrote:
Can you explain the 6dB advantage 2m has over 70cm? I've seen it here on the amsat-bb, and in the mesh realm when comparing 2.4GHz and 5.8GHz WiFi gear, but it still hasn't "clicked."
73 de KE5GDB
On Tue, Jun 16, 2015 at 6:56 PM, Paul Stoetzer [email protected] wrote:
Nick,
It should be even stronger than AO-27's 500 mW, AO-27 had a 70cm downlink, the EO-80 downlink is on 2 meters, so EO-80's signal should be up to 9 dB stronger than AO-27 (12 dB stronger if they run it at 1 watt).
73,
Paul, N8HM
On Tue, Jun 16, 2015 at 7:49 PM, Nicholas Mahr [email protected] wrote:
Thats very good news, Hopefully the two get activated before field
day?
Im
most looking forward to EO-80, It should be like AO-27 with 500Mw or
1W.
Good to know both are working well and wish a long life to them.
73 KE8AKW _______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring
membership.
Opinions expressed
are solely those of the author, and do not reflect the official views
of AMSAT-NA.
Not an AMSAT-NA member? Join now to support the amateur satellite
program!
Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring
membership.
Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite
program!
Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
-- Andrew Koenig
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb _______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Mode A would be fun, but equipment to work VHF/UHF is so common these days, I'm not sure there's much point in a 10m downlink. Mode B and Mode J are really not that much more difficult than working Mode A and have advantages (noise floor and antenna size, especially).
The real problem is deploying a good 10m antenna from a cubesat to produce a decent signal on the ground. 10m uplinks, on the other hand, are something to look into (as W2RS has presented in numerous forums). With NO-84, we now have a good experimental 10m uplink to test out. Since ground stations can usually increase power to compensate from a loaded antenna on the satellite, the use of a short antenna from a cubesat for an uplink receiver isn't as much of a problem.
73,
Paul, N8HM
On Wed, Jun 17, 2015 at 12:43 PM, Joe [email protected] wrote:
why can we not get an old skool mode "A" back?
Joe WB9SBD Sig The Original Rolling Ball Clock Idle Tyme Idle-Tyme.com http://www.idle-tyme.com
On 6/17/2015 11:26 AM, Robert Bruninga wrote:
I also am a proponent ot using 2m for weak downlinks because of the 9 dB advantage. But it has been pointed out to me that there is a higher background noise component that needs to be considered. I have not done this. My assumption is that the noise floor at 2m is maybe about 3 dB worse than at 70cm?
So 2m still wins, but I'm not sure of what the real noise floor is.
Bob, WB4aPR
-----Original Message----- From: AMSAT-BB [mailto:[email protected]] On Behalf Of Zach Leffke Sent: Wednesday, June 17, 2015 11:23 AM To: [email protected] Subject: Re: [amsat-bb] EO-80 FM Transponder Tested
Paul beat me to the punch as I was typing up my response, but I'm sending it anyway:
Path Loss. -> function of lambda (wavelength) squared. So all other things being equal (antenna gains, power levels, range, etc.), you can look at the power ratio of the two.
Rough calculation (going from 2m to 70cm): 10log[(0.70/2)^2] = -9.1 dB OR Rough calculation (going from 70cm to 2m): 10log[(2/0.7)^2] = +9.1 dB
The thing to watch out for is antenna gains on the ground. The arrow for example has more gain on 70cm (7el) than it does on 2m (3el). So while 2m has a 9-ish dB improvement over 70cm in terms of path loss, the receiver may not see the full 9dB because of the difference in gains on the antenna between the two bands.
Again VERY rough approximation (for demonstration purposes only): 3el yagi -> call it 7.5 ish dB of gain 7el yagi -> call it 11.5 ish dB of gain so, about 4 dB of LOST gain (going from 70cm to 2m using the arrow example).
So net gain going from 70cm to 2m (all other things equal except the gains on the arrow antenna) 9dB - 4dB = 5dB
so your typo was actually fairly close :-) for those planning to use their existing setup for the new birds.
-Zach, KJ4QLP
On 6/17/2015 10:43 AM, Andrew Koenig wrote:
*9dB (typo)
On Wed, Jun 17, 2015 at 9:42 AM, Andrew Koenig [email protected] wrote:
Can you explain the 6dB advantage 2m has over 70cm? I've seen it here on the amsat-bb, and in the mesh realm when comparing 2.4GHz and 5.8GHz WiFi gear, but it still hasn't "clicked."
73 de KE5GDB
On Tue, Jun 16, 2015 at 6:56 PM, Paul Stoetzer [email protected] wrote:
Nick,
It should be even stronger than AO-27's 500 mW, AO-27 had a 70cm downlink, the EO-80 downlink is on 2 meters, so EO-80's signal should be up to 9 dB stronger than AO-27 (12 dB stronger if they run it at 1 watt).
73,
Paul, N8HM
On Tue, Jun 16, 2015 at 7:49 PM, Nicholas Mahr [email protected] wrote:
Thats very good news, Hopefully the two get activated before field
day?
Im
most looking forward to EO-80, It should be like AO-27 with 500Mw or
1W.
Good to know both are working well and wish a long life to them.
73 KE8AKW _______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring
membership.
Opinions expressed
are solely those of the author, and do not reflect the official views
of AMSAT-NA.
Not an AMSAT-NA member? Join now to support the amateur satellite
program!
Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring
membership.
Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite
program!
Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
-- Andrew Koenig
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb _______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Results of Ambient RF Environment and Noise Floor Measurements Taken in the U.S. in 2004 and 2005 https://www.wmo.int/pages/prog/www/TEM/SG-RFC06/Ambient-RF-noise.pdf
73 Trevor M5AKA
Wow, If I read that correctly the charts are showing almost 20 dB or more higher noisefloor measurements on VHF than UHF. That is a huge difference. But in the text they say it is "30 dB" higher. I haven’t had time to dig out why the say that, but at a first cut, this shows the 9 dB link advantage of VHF over UHF vanishes at the ground station trying to hear a weak signal in the noise...
I did not have time to thouroughly digest the report. SO may have jumped to the wrong conclusion based on the details.
Bob, WB4aPR
-----Original Message----- From: AMSAT-BB [mailto:[email protected]] On Behalf Of M5AKA Sent: Wednesday, June 17, 2015 1:23 PM To: AMSAT BB Subject: Re: [amsat-bb] EO-80 FM Transponder Tested (noise floor?)
Results of Ambient RF Environment and Noise Floor Measurements Taken in the U.S. in 2004 and 2005 https://www.wmo.int/pages/prog/www/TEM/SG-RFC06/Ambient-RF-noise.pdf
73 Trevor M5AKA
_______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Hello - which satellites should we use for Field Day next week?
Thanks!
Any of them that are working!
Right now that's AO-7, AO-73, FO-29, SO-50, NO-84, and the ISS digipeater.
Be sure to do a dry run with your setup before setting up and good luck.
73,
Paul, N8HM
On Wed, Jun 17, 2015 at 9:39 PM, Stu [email protected] wrote:
Hello - which satellites should we use for Field Day next week?
Thanks! _______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Thanks for the info, Paul. Good advice.
Sent from my iPad
On Jun 17, 2015, at 9:41 PM, Paul Stoetzer [email protected] wrote:
Any of them that are working!
Right now that's AO-7, AO-73, FO-29, SO-50, NO-84, and the ISS digipeater.
Be sure to do a dry run with your setup before setting up and good luck.
73,
Paul, N8HM
On Wed, Jun 17, 2015 at 9:39 PM, Stu [email protected] wrote: Hello - which satellites should we use for Field Day next week?
Thanks! _______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Yes, and yes!
I'll be setting up in my back yard Thursday, so I'll be on from DM03 if anybody needs the grid.
73, Jim KQ6EA
On 06/18/2015 01:41 AM, Paul Stoetzer wrote:
Any of them that are working!
Right now that's AO-7, AO-73, FO-29, SO-50, NO-84, and the ISS digipeater.
Be sure to do a dry run with your setup before setting up and good luck.
73,
Paul, N8HM
On Wed, Jun 17, 2015 at 9:39 PM, Stu [email protected] wrote:
Hello - which satellites should we use for Field Day next week?
Thanks! _______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
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