: Re: [time-nuts] Mounting GPS Antenna on Steel Roof
In a message dated 08/03/2008 13:29:42 GMT Standard Time, [EMAIL PROTECTED]
writes:
The MAX232, like all RS-232 interface chips I have ever come across, inverts
the signal.
That'll explain
In a message dated 08/03/2008 03:57:02 GMT Standard Time,
[EMAIL PROTECTED] writes:
The inverter is required because the Motorola GPS receiver uses TTL and
the PC serial port uses RS232.
RS232 uses a positive voltage of +3 to +25 volts to indicate a logic
zero, and a negative voltage of
: [time-nuts] Mounting GPS Antenna on Steel Roof
In a message dated 08/03/2008 03:57:02 GMT Standard Time,
[EMAIL PROTECTED] writes:
The inverter is required because the Motorola GPS receiver
uses TTL and the PC serial port uses RS232.
RS232 uses a positive voltage of +3 to +25 volts
In a message dated 08/03/2008 13:29:42 GMT Standard Time, [EMAIL PROTECTED]
writes:
The MAX232, like all RS-232 interface chips I have ever come across, inverts
the signal.
That'll explain it then:-)
___
time-nuts
Well, I plugged my Oncore UT+ into my PC and it didn't work until I
put a level shifter in... no damage but no data either. So far I've
been lucky in that every device I tried that needed a level shifter
wasn't damaged by the lack of one.
The normal MAX232 type level shifters include an
Hal Murray wrote:
Well, I plugged my Oncore UT+ into my PC and it didn't work until I
put a level shifter in... no damage but no data either. So far I've
been lucky in that every device I tried that needed a level shifter
wasn't damaged by the lack of one.
The normal MAX232 type level
Quoth Hal Murray at 2008-03-07 19:59...
The normal MAX232 type level shifters include an inverter.
So even if the voltage levels work without a level shifter, the signal will
be upside down.
I'm building my test board with a hex inverter that I'm actually using
to buffer the 1PPS signal.
The inverter is required because the Motorola GPS receiver uses TTL and
the PC serial port uses RS232.
RS232 uses a positive voltage of +3 to +25 volts to indicate a logic
zero, and a negative voltage of -3 to -25 volts to indicate a logic one.
Brian KD4FM
Bruce Griffiths wrote:
Hal Murray
Attached is a interface for an Oncore VP receiver. You will have to
check - I believe the GT and UT use the same connections as the VP.
Brian Kirby wrote:
The inverter is required because the Motorola GPS receiver uses TTL and
the PC serial port uses RS232.
RS232 uses a positive voltage of
Quoth Brian Kirby at 2008-03-08 14:46...
Attached is a interface for an Oncore VP receiver. You will have to
check - I believe the GT and UT use the same connections as the VP.
Thanks Brian - that's pretty close to what I've come up with apart from
the fact that I'm putting isolation (TI
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Mounting GPS Antenna on Steel Roof
Quoth Brian Kirby at 2008-03-08 14:46...
Attached is a interface for an Oncore VP receiver. You
will have to
check - I believe the GT and UT use the same connections as the VP
I will be doing (4) as soon as I've found the time to make up a TTL to
RS232 board.
I suggest trying it without anything fancy.
All the GPS toys I've tried work fine without any conversion gear.
The normal TTL to RS-232 chips include an inverter. That will break things
unless you add
Quoth Hal Murray at 2008-03-06 20:07...
I will be doing (4) as soon as I've found the time to make up a TTL to
RS232 board.
I suggest trying it without anything fancy.
All the GPS toys I've tried work fine without any conversion gear.
The normal TTL to RS-232 chips include an inverter.
Matthew Smith wrote:
Quoth Hal Murray at 2008-03-06 20:07...
I will be doing (4) as soon as I've found the time to make up a TTL to
RS232 board.
I suggest trying it without anything fancy.
All the GPS toys I've tried work fine without any conversion gear.
The normal TTL to
On Thu, Mar 6, 2008 at 3:08 PM, Matthew Smith [EMAIL PROTECTED] wrote:
So my Trimble ACE II and Moto Oncore modules will tolerate RS232 levels
without conversion? Are we absolutely sure on this - I don't want to
fry anything!
Well, I plugged my Oncore UT+ into my PC and it didn't work
So my Trimble ACE II and Moto Oncore modules will tolerate RS232 levels
without conversion? Are we absolutely sure on this - I don't want to
fry anything!
Bruce, Chris, thanks for the confirmation.
I'll go back to the idea of using the MAX232 equivalent as originally
planned.
I'm also
Chris Kuethe wrote:
On Thu, Mar 6, 2008 at 3:08 PM, Matthew Smith [EMAIL PROTECTED] wrote:
So my Trimble ACE II and Moto Oncore modules will tolerate RS232 levels
without conversion? Are we absolutely sure on this - I don't want to
fry anything!
Well, I plugged my Oncore UT+
Matthew Smith wrote:
So my Trimble ACE II and Moto Oncore modules will tolerate RS232 levels
without conversion? Are we absolutely sure on this - I don't want to
fry anything!
Bruce, Chris, thanks for the confirmation.
I'll go back to the idea of using the MAX232 equivalent as
Quoth Rob Kimberley at 2008-03-05 02:45...
You mentioned Time Server..is this your only GPS or do you have other more
accurate timing requirements? Unless you are working on nanosecond type
accuracy, I don't see that mounting your antenna on the metal roof is going
to cause you any practical
Matthew,
You hit the nail on the head with item 4!
Good luck.
Rob K
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Matthew Smith
Sent: 04 March 2008 21:17
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Mounting GPS
Matthew Smith wrote:
Hi Folks
Further to the cable splicing thread, I have been having a discussions
off-list with Didier regarding the placement of my antennas on the ridge
cap of my roof.
There is certain concern that I may have issues with reflections - can
anyone confirm whether or not
Hi Matthew:
Some antennas are receptive to signals coming up from below.
Since the signal is circularly polarized the first reflection is supposed to be
down something like 20 dB, but the second reflection will be much stronger, so
you would also need to look at those.
Have Fun,
Brooke
Brooke Clarke wrote:
Hi Matthew:
Some antennas are receptive to signals coming up from below.
Since the signal is circularly polarized the first reflection is supposed to
be
down something like 20 dB, but the second reflection will be much stronger,
so
you would also need to look at
for maximum
satellites.
Rob Kimberley
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Matthew Smith
Sent: 04 March 2008 05:08
To: Time Nuts List
Subject: [time-nuts] Mounting GPS Antenna on Steel Roof
Hi Folks
Further to the cable splicing thread, I have been
Quoth Rob Kimberley at 2008-03-04 19:29...
Height of antenna is not important, but being clear of obstructions and
large metallic objects are. Can you mount it on a pole at the end of the
garden?
I can, but the end of the garden is some 50 metres from the house, which
brings back my concern
] On
Behalf Of Matthew Smith
Sent: Tuesday, March 04, 2008 1:36 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Mounting GPS Antenna on Steel Roof
Quoth Rob Kimberley at 2008-03-04 19:29...
Height of antenna is not important, but being clear of obstructions
: [time-nuts] Mounting GPS Antenna on Steel Roof
Quoth Rob Kimberley at 2008-03-04 19:29...
Height of antenna is not important, but being clear of obstructions and
large metallic objects are. Can you mount it on a pole at the end of the
garden?
I can, but the end of the garden is some 50 metres from
.
Regards,
Keith
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Matthew Smith
Sent: Tuesday, March 04, 2008 1:36 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Mounting GPS Antenna on Steel Roof
Quoth
Brooke Clarke wrote:
Hi Matthew:
Some antennas are receptive to signals coming up from below.
Since the signal is circularly polarized the first reflection is supposed to
be
down something like 20 dB, but the second reflection will be much stronger,
so
you would also need to look at
Brooke Clarke wrote:
Hi Bruce:
Yes.
There was a prior thread about using X band offset parabolic TV
antennas with a stock GPS antenna. The idea being to aim the beam at
a WAAS GPS satellite. I heard it worked well even though cross pol
should have made for poor results.
How to find
time and frequency measurement
Subject: Re: [time-nuts] Mounting GPS Antenna on Steel Roof
Quoth Rob Kimberley at 2008-03-04 19:29...
Height of antenna is not important, but being clear of obstructions and
large metallic objects are. Can you mount it on a pole at the end of the
garden?
I can
:[EMAIL PROTECTED] On
Behalf Of Matthew Smith
Sent: Tuesday, March 04, 2008 3:36 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Mounting GPS Antenna on Steel Roof
Quoth Rob Kimberley at 2008-03-04 19:29...
Height of antenna is not important, but being
Hi Folks
Further to the cable splicing thread, I have been having a discussions
off-list with Didier regarding the placement of my antennas on the ridge
cap of my roof.
There is certain concern that I may have issues with reflections - can
anyone confirm whether or not this is the case?
Here is
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