Article: 141304 of sci.geo.satellite-nav From: wayne@nospam.novacomtech.com (C. Wayne Buhrman) Newsgroups: sci.geo.satellite-nav Subject: Re: Cheap 1pps unit? Date: Tue, 25 Apr 2000 15:58:23 GMT Organization: NOVACOM Technologies Lines: 62 Message-ID: <3905c070.8451890@news.planetcable.net> References: <3903810B.22B2@attglobal.net> <39038F5B.DCAFC5E4@cornell.edu> Reply-To: wayne@nospam.novacomtech.com X-Complaints-To: newsabuse@supernews.com X-Newsreader: Forte Agent 1.01/32.397 X-No-Archive: yes MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Path: news1.meer.net!news3.best.com!news1.best.com!su-news-hub1.bbnplanet.com!cpk-news-hub1.bbnplanet.com!news.gtei.net!feeder.qis.net!sn-xit-01!supernews.com!sn-inject-01!corp.supernews.com!not-for-mail Xref: news1.meer.net sci.geo.satellite-nav:141304 Bob, Do you know what pin of the Tripmate has the 1 pps signal? Thanks. Wayne On Mon, 24 Apr 2000 08:09:52 -0700, "John Galvin" wrote: >Bob: > >Have you actually done this to a genuine Rand Mcnally (Talon) GPS receiver? >My contact at Talon told me that the 1pps output is NOT PRESENT on the Rand >Mcnally receiver due to rom space limitations. I have looked for the 1pps >on the Rand Mcnally anyway and did not find it. I did see the 10khz signal >you mentioned though. I suppose one could rig up a divide by 10k circuit, >but the output would not be aligned to UTC (or is it GPS?) time. > >The 1pps output is present, I believe, on the DeLorme Tripmate. Which was >available at one time, on DeLorme's website for $79.95 (receiver only, no >software). It is possible that it is also present on DeLorme's Earthmate, >too, but I wouldn't recommend going that route, as Earthmate costs as much >as a Garmin 35 OEM board, that definitely has a proper 1pps output and there >is no surgery required. > >John Galvin > > >Bob wrote in message <39038F5B.DCAFC5E4@cornell.edu>... >>Well, if you can do a little surgery, Rand-McNally sells a package >>called Street Finder Deluxe. Staples has it for $99.00. Included is a >>mouse sized GPS receiver that's based on the Scorpio (Rockwell Jupiter) >>chipset. This thing can run on 4.6 to 18 volts, and includes NMEA >>output, as well as the FULLY functional Rockwell binary mode. As for >>your 1 PPS output, it's present on pin 95 of the Scorpio DSP. Chip is >>labeled 11577-11. To identify pin 95, place the board so the labeling on >>the DSP is readable in the normal way ie; left to right. Chip counts >>like this - left side is pin 1 to 36 down. Bottom, 37 to 72 left to >>right. 73 to 108 up. 109 to 144 right to left. Also present on pin 96 is >>a 10khz clock which is synchronous with the TM (1pps). They work like >>this - At UTC 1 second boundary, the TM line goes high and stays high >>for 257 cycles of the 10 kc clock. TM goes low on the positive >>transition of the 258th count of the 10 kc clock. Surgery required, but >>it's real cheap. >> >>Ken Hamer wrote: >> >>> Hi all. >>> >>> I'm looking for an inexpensive GPS unit with a 1pps output. I don't >>> need the 50ns accuracy, but would like better than ms accuracy. In >>> fact, I don't even need the time output. All I need is the pulse. >>> >>> I'd be grateful if anyone could point me in that direction. >>> >>> Thanks in advance. >> >> > > Article: 141330 of sci.geo.satellite-nav From: Grossman Family Newsgroups: sci.geo.satellite-nav Subject: Re: Cheap 1pps unit? Date: Tue, 25 Apr 2000 20:47:10 -0400 Lines: 69 Message-ID: <39063C8E.F7B4456@rcn.com> References: <3903810B.22B2@attglobal.net> <39038F5B.DCAFC5E4@cornell.edu> <3905c070.8451890@news.planetcable.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Trace: S7oLkmwJfFI60ohFPmjobKGN7J9M+oop8YIMhfIs3J8= X-Complaints-To: abuse@rcn.com NNTP-Posting-Date: 26 Apr 2000 00:47:10 GMT To: wayne@nospam.novacomtech.com X-Accept-Language: en,zh-CN X-Mailer: Mozilla 4.61 [en] (Win98; U) Path: news1.meer.net!news3.best.com!news2.best.com!feed1.news.rcn.net!rcn!not-for-mail Xref: news1.meer.net sci.geo.satellite-nav:141330 The TM does have 1 PPS, and offhand I don't remember what pin its on BUT I know its their.......I've hooked it up and brought it out the on a wire to an external counter! The problem is...its currently (ie the TM) in a weatherproof box up on my roof! Besides it being used as a local NTP server its broadcasting local DGPS corrections on a HAM band. "C. Wayne Buhrman" wrote: > Bob, > Do you know what pin of the Tripmate has the 1 pps signal? > > Thanks. > Wayne > > On Mon, 24 Apr 2000 08:09:52 -0700, "John Galvin" > wrote: > > >Bob: > > > >Have you actually done this to a genuine Rand Mcnally (Talon) GPS receiver? > >My contact at Talon told me that the 1pps output is NOT PRESENT on the Rand > >Mcnally receiver due to rom space limitations. I have looked for the 1pps > >on the Rand Mcnally anyway and did not find it. I did see the 10khz signal > >you mentioned though. I suppose one could rig up a divide by 10k circuit, > >but the output would not be aligned to UTC (or is it GPS?) time. > > > >The 1pps output is present, I believe, on the DeLorme Tripmate. Which was > >available at one time, on DeLorme's website for $79.95 (receiver only, no > >software). It is possible that it is also present on DeLorme's Earthmate, > >too, but I wouldn't recommend going that route, as Earthmate costs as much > >as a Garmin 35 OEM board, that definitely has a proper 1pps output and there > >is no surgery required. > > > >John Galvin > > > > > >Bob wrote in message <39038F5B.DCAFC5E4@cornell.edu>... > >>Well, if you can do a little surgery, Rand-McNally sells a package > >>called Street Finder Deluxe. Staples has it for $99.00. Included is a > >>mouse sized GPS receiver that's based on the Scorpio (Rockwell Jupiter) > >>chipset. This thing can run on 4.6 to 18 volts, and includes NMEA > >>output, as well as the FULLY functional Rockwell binary mode. As for > >>your 1 PPS output, it's present on pin 95 of the Scorpio DSP. Chip is > >>labeled 11577-11. To identify pin 95, place the board so the labeling on > >>the DSP is readable in the normal way ie; left to right. Chip counts > >>like this - left side is pin 1 to 36 down. Bottom, 37 to 72 left to > >>right. 73 to 108 up. 109 to 144 right to left. Also present on pin 96 is > >>a 10khz clock which is synchronous with the TM (1pps). They work like > >>this - At UTC 1 second boundary, the TM line goes high and stays high > >>for 257 cycles of the 10 kc clock. TM goes low on the positive > >>transition of the 258th count of the 10 kc clock. Surgery required, but > >>it's real cheap. > >> > >>Ken Hamer wrote: > >> > >>> Hi all. > >>> > >>> I'm looking for an inexpensive GPS unit with a 1pps output. I don't > >>> need the 50ns accuracy, but would like better than ms accuracy. In > >>> fact, I don't even need the time output. All I need is the pulse. > >>> > >>> I'd be grateful if anyone could point me in that direction. > >>> > >>> Thanks in advance. > >> > >> > > > > Article: 141412 of sci.geo.satellite-nav Reply-To: "John Galvin" From: "John Galvin" Newsgroups: sci.geo.satellite-nav References: <3903810B.22B2@attglobal.net> <39038F5B.DCAFC5E4@cornell.edu> <3905c070.8451890@news.planetcable.net> <39063F78.A6D167E4@cornell.edu> Subject: Re: Cheap 1pps unit? Lines: 40 X-Newsreader: Microsoft Outlook Express 4.72.3110.5 X-MimeOLE: Produced By Microsoft MimeOLE V4.72.3110.3 Message-ID: Date: Wed, 26 Apr 2000 16:59:26 -0700 NNTP-Posting-Host: 207.214.213.57 X-Complaints-To: abuse@swbell.net X-Trace: news.swbell.net 956794475 207.214.213.57 (Wed, 26 Apr 2000 19:14:35 CDT) NNTP-Posting-Date: Wed, 26 Apr 2000 19:14:35 CDT Organization: SBC Internet Services Path: news1.meer.net!news3.best.com!news2.best.com!news.maxwell.syr.edu!newsfeed.mathworks.com!cyclone.swbell.net!news.swbell.net.POSTED!not-for-mail Xref: news1.meer.net sci.geo.satellite-nav:141412 Bob: Yes, it is enabled on the Tripmate. It SHOULD be on pin 95. Way back, more than a year ago, Martin Grossman posted here, that the correct pin was pin 50. Looking at the Scorpio DSP chip, I noticed that, if you erroneously count pins in the clockwise direction, starting from pin 1, it will appear that the 1 pps signal is on pin 50. Counting correctly (counterclockwise), from pin 1, the 1 pps signal is on pin 95, as you have indicated. On the Rand Mcnally, the signal is there, but the message type 1108, UTC Time Mark Pulse Output Message, cannot be enabled. On other Zodiac based receivers, this message is guaranteed to precede the pulse by 400 milliseconds. It provides the info for what the time will be at the rising edge of the pulse. Kind of like an electronic version of "at the tone, the time will be ...". You can probably get by without message type 1108, if your application is not critical. Relying on any other message to predict what the time is at the rising edge of the 1 pps, is quite risky, as the serial I/O manager can and does replicate other messages with the same time tag as previous messages, in the case when no new data is available and the message's timing characteristics dictates that a message be output anyway. Message type 1108 is guaranteed not to be replicated. John Galvin Bob wrote in message <39063F78.A6D167E4@cornell.edu>... >Same chip (but it's the 5 volt version) but I'm not sure it's enabled on the >Delorme Tripmate. > >"C. Wayne Buhrman" wrote: > >> Bob, >> Do you know what pin of the Tripmate has the 1 pps signal? >> > > Article: 141412 of sci.geo.satellite-nav Reply-To: "John Galvin" From: "John Galvin" Newsgroups: sci.geo.satellite-nav References: <3903810B.22B2@attglobal.net> <39038F5B.DCAFC5E4@cornell.edu> <3905c070.8451890@news.planetcable.net> <39063F78.A6D167E4@cornell.edu> Subject: Re: Cheap 1pps unit? Lines: 40 X-Newsreader: Microsoft Outlook Express 4.72.3110.5 X-MimeOLE: Produced By Microsoft MimeOLE V4.72.3110.3 Message-ID: Date: Wed, 26 Apr 2000 16:59:26 -0700 NNTP-Posting-Host: 207.214.213.57 X-Complaints-To: abuse@swbell.net X-Trace: news.swbell.net 956794475 207.214.213.57 (Wed, 26 Apr 2000 19:14:35 CDT) NNTP-Posting-Date: Wed, 26 Apr 2000 19:14:35 CDT Organization: SBC Internet Services Path: news1.meer.net!news3.best.com!news2.best.com!news.maxwell.syr.edu!newsfeed.mathworks.com!cyclone.swbell.net!news.swbell.net.POSTED!not-for-mail Xref: news1.meer.net sci.geo.satellite-nav:141412 Bob: Yes, it is enabled on the Tripmate. It SHOULD be on pin 95. Way back, more than a year ago, Martin Grossman posted here, that the correct pin was pin 50. Looking at the Scorpio DSP chip, I noticed that, if you erroneously count pins in the clockwise direction, starting from pin 1, it will appear that the 1 pps signal is on pin 50. Counting correctly (counterclockwise), from pin 1, the 1 pps signal is on pin 95, as you have indicated. On the Rand Mcnally, the signal is there, but the message type 1108, UTC Time Mark Pulse Output Message, cannot be enabled. On other Zodiac based receivers, this message is guaranteed to precede the pulse by 400 milliseconds. It provides the info for what the time will be at the rising edge of the pulse. Kind of like an electronic version of "at the tone, the time will be ...". You can probably get by without message type 1108, if your application is not critical. Relying on any other message to predict what the time is at the rising edge of the 1 pps, is quite risky, as the serial I/O manager can and does replicate other messages with the same time tag as previous messages, in the case when no new data is available and the message's timing characteristics dictates that a message be output anyway. Message type 1108 is guaranteed not to be replicated. John Galvin Bob wrote in message <39063F78.A6D167E4@cornell.edu>... >Same chip (but it's the 5 volt version) but I'm not sure it's enabled on the >Delorme Tripmate. > >"C. Wayne Buhrman" wrote: > >> Bob, >> Do you know what pin of the Tripmate has the 1 pps signal? >> > >