Re: [Elecraft] OT: 3Y0Z Bouvet Island DXpedition

[Wes Stewart]

Relax.

On 1/24/2018 7:13 PM, ab2tc wrote:

Hi again,

Well, the recent posts have indeed taken us farther OT. While the original
GPS 101 posting was excellent  information, we are now well past the
overload on GPS details (and politics). The ship is now well past South
Georgia Island. They acknowledge that their ship borne antennas leave them
with weak signals (both ways of course). Hopefully that will change once
they get their beams up on the island. Can we please drop the GPS subject?

AB2TC - Knut



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Re: [Elecraft] OT: 3Y0Z Bouvet Island DXpedition

[ab2tc]

Hi again,

Well, the recent posts have indeed taken us farther OT. While the original
GPS 101 posting was excellent  information, we are now well past the
overload on GPS details (and politics). The ship is now well past South
Georgia Island. They acknowledge that their ship borne antennas leave them
with weak signals (both ways of course). Hopefully that will change once
they get their beams up on the island. Can we please drop the GPS subject?

AB2TC - Knut


Dale Chayes wrote
> At the risk of taking us further off topic…..
> 
> SA was turned off in May of 2000 by executive order.
> https://www.gps.gov/systems/gps/modernization/sa/
> https://www.gps.gov/systems/gps/modernization/sa/;
> 





--
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Re: [Elecraft] OT: 3Y0Z Bouvet Island DXpedition

[Dale Chayes]

At the risk of taking us further off topic…..

SA was turned off in May of 2000 by executive order.
https://www.gps.gov/systems/gps/modernization/sa/ 


The position quality transition brought on by the shutdown of SA was a 
milestone event for the marine research community (among many others.) This 
event was captured at the time by many and is characterized by the amazing 
graph on the page above - fond memories.  Some (many of our tiny community) 
stayed up and watched the data show the transition in real-time - after 
stumbling around the world’s oceans for a decade it was AWESOME. 

I’ve been working with GPS/GNSS receivers (mostly on research ships at sea, but 
some geodesy) since the early 1980s when our “portable” (two full height relay 
racks) Y-set had two HP 2100s and a 9-track tape drive see: 
https://www.ion.org/museum/item_view.cfm?cid=7=9=43 
 (the picture 
only has the receiver hardware, it took serious comping in that era to derive 
real-time solutions and log the data. Now our cellphones and watches do it.)   
Moving that system from ship to ship set the bar for my Compaq “luggable” later 
on ;-)

A substantial part of the early orbit-correction data collection and analysis 
that led to differential GPS was led by the civilian surveying and geodesy 
community trying to figure out how to get high accuracy post-processed 
solutions during SA.  (Not unlike the amateur radio digital experiments that 
led to packet radio…

I still do no not take GPS (and GNSS) for granted.

-Dale KB1ZKD
---
"Getting out there and doing it; that’s what really counts. At the end of a 
career, at the end of anything, it’s not about the awards. It’s about the 
friends and family.” -Daryl Miller,  McKinley climbing ranger

> On Jan 24, 2018, at 17:41 , Fred Jensen  wrote:
> 
> Yep.  The "civilian channel" on GPS was a gift to everyone from the US 
> Department of Defense, I suppose they could turn it off if they so wish, but 
> it is so ingrained in today's culture that they won't.  Years ago, the 
> channel was purposely perturbed to limit the horizontal accuracy to something 
> between +/-100 to 200 meters.  It was called "Selective Availability."
> 
> The US Coast Guard [another branch of the US military] promptly installed GPS 
> receivers in very carefully surveyed key locations, and published the error 
> between the known position and the GPS reported position.  They called it 
> Differential GPS.  If you had a DGPS receiver, and were close enough to the 
> DGPS receiver, it would use the broadcast error to correct the received 
> position. In the US at least, they're still broadcasting from various sites 
> in the 280 – 460 KHz range which you can receive if your K3 has the new 
> synthesizer [and you have the BPSK decoder and a cheat-sheet for the format]. 
>  Over time, commercial interests also began doing this too.
> 
> Quite awhile back, someone in the guvmint must have realized that SA wasn't 
> really working all that well at limiting position precision on the civilian 
> channel and gave up.  The DGPS transmissions continue, or at least did in 
> 2015.  So much these days depends on GPS, it's hard to see the "100 ms 
> channel" going away.
> 
> 73,
> 
> Fred ["Skip"] K6DGW
> Sparks NV DM09dn
> Washoe County
> On 1/24/2018 11:18 AM, Ken Chandler wrote:
>> Course, Governments/Military have overall control over civilian use of the 
>> Birds!  or certainly use to have, whether that’s still the case I’m unsure!
>> 
>> 
>> 
>> Ken.. G0ORH
>> 
> 
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Re: [Elecraft] OT: 3Y0Z Bouvet Island DXpedition

[Fred Jensen]

Yep.  The "civilian channel" on GPS was a gift to everyone from the US 
Department of Defense, I suppose they could turn it off if they so wish, 
but it is so ingrained in today's culture that they won't.  Years ago, 
the channel was purposely perturbed to limit the horizontal accuracy to 
something between +/-100 to 200 meters.  It was called "Selective 
Availability."


The US Coast Guard [another branch of the US military] promptly 
installed GPS receivers in very carefully surveyed key locations, and 
published the error between the known position and the GPS reported 
position.  They called it Differential GPS.  If you had a DGPS receiver, 
and were close enough to the DGPS receiver, it would use the broadcast 
error to correct the received position. In the US at least, they're 
still broadcasting from various sites in the 280 – 460 KHz range which 
you can receive if your K3 has the new synthesizer [and you have the 
BPSK decoder and a cheat-sheet for the format].  Over time, commercial 
interests also began doing this too.


Quite awhile back, someone in the guvmint must have realized that SA 
wasn't really working all that well at limiting position precision on 
the civilian channel and gave up.  The DGPS transmissions continue, or 
at least did in 2015.  So much these days depends on GPS, it's hard to 
see the "100 ms channel" going away.


73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County
On 1/24/2018 11:18 AM, Ken Chandler wrote:

Course, Governments/Military have overall control over civilian use of the 
Birds!  or certainly use to have, whether that’s still the case I’m unsure!



Ken.. G0ORH



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[Elecraft] Elecraft SSB net logs

[Phil Shepard]

Here are two recent SSB net check-in lists:

Elecraft SSB Net 1-14-2018

WB9JNZ Eric IL K3 4017 Net Control

W0LRF Larry CO K3S 10531

K1NW Brian RI K3 4974

N4NRW Roger SC K3 1318

NC0JW Jim CO KX3 1356

K9ING Bob TX K3 5693 1st TIME CHECK IN

WM6P Steve GA K3S 11453

NS7P Phil OR K3 1826

W4RKS Jim TX K3 3618

KJ4ZSI Bud FL K3 4703

W1NGA Al CO KX3 2829

N9TF Gene IL K3S 10057

KB9AVO Paul IN K3S 11103

K6WVE Stan MI K3 650

W4DHL Doug TN K3 6433

ZL1PWD Peter New Zealand K3 139

K4GCJ Gary NC K3 1597

W7QHD Kurt CA KX3 8697

KG4UAL Tripp K2 3665

W7REK Glenn AZ K3 2843

K2COP Greg FL KX3 7359

W7DLP Preston WY IC7300

N9VTB George IL ICOM 7610

N9SRA Steve IL ICOM 7600

K7JG John WA KX3 3519


Elecraft SSB Net 1-21-2018

WB9JNZ Eric IL K3 4017 Net Control

N9SRA Steve IL ICOM 7600

W0LRF Larry CO K3S 10531

K1NW Brian RI K3 4974

AD5SX Paul NM K3 4625

NC0JW Jim CO KX3 1356

K4GCJ Gary NC K3 1597

WM5F Dwight ID KX3 8045

KE7FSD Al AZ K3 8532 QRP

W7QHD Kurt CA KX3 8697

KJ4ZSI Bud FL K3 4703

W7REK Glenn AZ K3 2843

K6WVE Stan MI K3 650

WM6P Steve GA K3S 11453

NS7P Phil OR K3 1826

ZL1PWD Peter New Zealand K3 139

N4NRW Roger SC K3 1318

K5RHD Randy NM KX3 1383

W1NGA Al CO KX3 2829

K7JG John WA KX3 3519

W7JJL John WA KX3 0993

W4RKS Jim TX K3 3618

WW4JF John TN K3S 11177

VE3LMS Grant ONT K2 4231 QRP

W2RWA Dick NY K2 2601

LK4JM John Al IC 7200



Thanks to Eric, WB9JNZ, for supplying these logs. See you next Sunday at 1800z.

73,
Phil, NS7P
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Re: [Elecraft] OT: 3Y0Z Bouvet Island DXpedition

[Ken Chandler]

Course, Governments/Military have overall control over civilian use of the 
Birds!  or certainly use to have, whether that’s still the case I’m unsure!



Ken.. G0ORH

Sent from my iPad


> On 24 Jan 2018, at 17:21, Fred Jensen  wrote:
> 
> The elevation changes seen with civilian GPS are the result of two fairly 
> fundamental issues:
> 
> 1.  A GPS receiver doesn't really "know" where actual sea level is, it uses a 
> mathematical model.  Since the earth is ellipsoidal-ish rather than spherical 
> on a large scale, and since there are smaller local variations, the model is 
> a trade-off between accuracy and complexity.  On State Route 37 just north of 
> San Francisco, you are immediately adjacent to San Pablo Bay and can see that 
> you're about 10 ft above it.  My Garmin GPS pegs my elevation at 61 ft.
> 
> 2.  The second is "dilution of precision," or DOP.  The relative positions of 
> the satellites in the sky change constantly, and finding your coordinates is 
> a process of finding the intersection point of lines of position [LOP] from 
> multiple satellites.  When the satellites are scattered all over the sky, 
> many of the LOP's intersect at large angles [90 deg is ideal] and the 
> intersection is well defined.  If the satellites are more or less lined up in 
> one area of the sky, the LOP's tend to intersect at smaller angles and the 
> exact intersection point is less well defined.  This is Horizontal DOP or 
> HDOP.
> 
> Unfortunately, when it comes to elevation [VDOP], roughly half the satellites 
> are below the horizon at any given time, there are thus fewer LOP's to work 
> with, and the probability of finding large-angle LOP's is inherently lower.  
> Hence, VDOP is usually [almost always] greater than HDOP.
> 
> Thus endeth GPS 101.
> 
> I also think they are communicating using some service on the Iridium 
> constellation which is probably expensive, and the ship is only making around 
> 10 kts or so, so more frequent updates wouldn't indicate much.  Given the 
> overall expense of this expedition however, communications costs are probably 
> below the round-off. [:-)
> 
> 73,
> 
> Fred ["Skip"] K6DGW
> Sparks NV DM09dn
> Washoe County
> 
>> On 1/24/2018 5:52 AM, Bayard Coolidge, N1HO via Elecraft wrote:
>> The elevation discrepancies are normal - I see the same effect whendriving 
>> around down here in South Florida, randomly dropping to 10-20feet below sea 
>> level. The civilian GPS systems are not configured forextreme elevation 
>> accuracy, particularly when close to sea level.
>> 
>> The main web site's position reporting may be outdated because, I think,that 
>> they're relaying their position via satellite (Iridium, perhaps?) whichcan 
>> get pretty expensive. Given the length of the journey, it's probablynot 
>> worthwhile providing hour-by-hour position updates. They'll get therewhen 
>> they get there, and they'll get on the air after they get things set up.
>> 73,
>> Brandy, N1HO (EL96xh)
>> 
> 
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Re: [Elecraft] OT: 3Y0Z Bouvet Island DXpedition

[Fred Jensen]

The elevation changes seen with civilian GPS are the result of two 
fairly fundamental issues:


1.  A GPS receiver doesn't really "know" where actual sea level is, it 
uses a mathematical model.  Since the earth is ellipsoidal-ish rather 
than spherical on a large scale, and since there are smaller local 
variations, the model is a trade-off between accuracy and complexity.  
On State Route 37 just north of San Francisco, you are immediately 
adjacent to San Pablo Bay and can see that you're about 10 ft above it.  
My Garmin GPS pegs my elevation at 61 ft.


2.  The second is "dilution of precision," or DOP.  The relative 
positions of the satellites in the sky change constantly, and finding 
your coordinates is a process of finding the intersection point of lines 
of position [LOP] from multiple satellites.  When the satellites are 
scattered all over the sky, many of the LOP's intersect at large angles 
[90 deg is ideal] and the intersection is well defined.  If the 
satellites are more or less lined up in one area of the sky, the LOP's 
tend to intersect at smaller angles and the exact intersection point is 
less well defined.  This is Horizontal DOP or HDOP.


Unfortunately, when it comes to elevation [VDOP], roughly half the 
satellites are below the horizon at any given time, there are thus fewer 
LOP's to work with, and the probability of finding large-angle LOP's is 
inherently lower.  Hence, VDOP is usually [almost always] greater than HDOP.


Thus endeth GPS 101.

I also think they are communicating using some service on the Iridium 
constellation which is probably expensive, and the ship is only making 
around 10 kts or so, so more frequent updates wouldn't indicate much.  
Given the overall expense of this expedition however, communications 
costs are probably below the round-off. [:-)


73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 1/24/2018 5:52 AM, Bayard Coolidge, N1HO via Elecraft wrote:

The elevation discrepancies are normal - I see the same effect whendriving 
around down here in South Florida, randomly dropping to 10-20feet below sea 
level. The civilian GPS systems are not configured forextreme elevation 
accuracy, particularly when close to sea level.

The main web site's position reporting may be outdated because, I think,that 
they're relaying their position via satellite (Iridium, perhaps?) whichcan get 
pretty expensive. Given the length of the journey, it's probablynot worthwhile 
providing hour-by-hour position updates. They'll get therewhen they get there, 
and they'll get on the air after they get things set up.
73,
Brandy, N1HO (EL96xh)



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[Elecraft] Wanted: K1 filter board

[Scott via Elecraft]

Please email me if you have a -2 or -4 board.  I'm looking for 80m, so any of 
the following would be acceptable:
 bare board, bare board with 80 parts unassembledassembled board with 80m

Thanks,Scott N1ST
  
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Re: [Elecraft] Array Solutions Lightning Arrestor

[Chris R]

For those who might be interested, http://kf7p.com/KF7P/Welcome.html sells
Morgan Arrestors and many other excellent products for towers, entrance
panels, grounding, ferrite chokes, etc. He also has an excellent set of
references on his Tech page.

No, no connection to the company; just a satisfied customer.

73 Chris NW6V
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[Elecraft] K3 Power Reading/SWR/ALC Problem

[Paul Christensen]

> "This cable worked for me for several years but recently failed.  Bring
some extra jumper coax with you..."

Karin,

Many thanks.  I have several extra RG-400 jumpers that can be used as well
as confirming if the issue appears on ANT-2.  Schottky diodes arrive
tomorrow, so I'll be ready later this week.  I'll report back on the final
fix.

Paul, W9AC

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Re: [Elecraft] OT: 3Y0Z Bouvet Island DXpedition

[Bayard Coolidge, N1HO via Elecraft]

The elevation discrepancies are normal - I see the same effect whendriving 
around down here in South Florida, randomly dropping to 10-20feet below sea 
level. The civilian GPS systems are not configured forextreme elevation 
accuracy, particularly when close to sea level.

The main web site's position reporting may be outdated because, I think,that 
they're relaying their position via satellite (Iridium, perhaps?) whichcan get 
pretty expensive. Given the length of the journey, it's probablynot worthwhile 
providing hour-by-hour position updates. They'll get therewhen they get there, 
and they'll get on the air after they get things set up.
73,
Brandy, N1HO (EL96xh)

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