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ZL3AI > APRDIG 01.04.04 15:53l 232 Lines 9540 Bytes #999 (0) @ WW
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From: ZL3AI@ZL3VML.#80.NZL.OC
To : APRDIG@WW
Subject: Re: New tracker design suggestions (fwd)
From: "Scott Miller" <scott@opentrac.org>
Date: Mon, 29 Mar 2004 10:54:13 -0800
X-Message-Number: 23
>This would be good, but I want a tracker that has a separate port for
>connection to a $50 Palm V or VII unit. I don't necessarily want the
>tracker to see locations, but definitely want the tracker to be able to send
>a message from a list of preprepared feature messages.
In the future, I'd like to provide Bluetooth support. Since some PDAs
already work with Bluetooth GPS receivers, you could connect a hardwired GPS
to the tracker and have it pass the NMEA data, along with injected
waypoints, over Bluetooth. Ideally you'd run custom software on the PDA
that'd let you draw search areas, plot DF bearings, and so on. Everything
but the PDA would stay in your backpack, eliminating all of the cable
clutter.
I've found PDA mapping programs, and PDA APRS programs, but nothing with the
mix of capabilities I need.
>Also want the cabling and connections to be ruggedized. DB-9s and power
>connections that can't be screwed down are just asking for trouble in the
>field.
The DB9's aren't a problem. Not sure about power. You could use the RJ45
input, since it'll be wired to accept +8V from Kenwood mic connectors. I'd
been planning on a simple coaxial plug, but those do tend to work loose.
Running on an internal NiMH battery pack would eliminate that problem.
A pushbutton-style power switch like the KPC-3's might also be a problem
when it's shoved in a pack. I'll have to keep that in mind. Maybe a bypass
jumper?
Scott
N1VG
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Subject: Re: New tracker design suggestions
From: David VanHorn <dvanhorn@cedar.net>
Date: Mon, 29 Mar 2004 13:57:18 -0500
X-Message-Number: 24
At 10:35 AM 3/29/2004 -0800, Scott Miller wrote:
>>Assuming perfect power, would you ever get that low on an FM rig, without
>the SNR going to hell first?
>
>I suppose not, but then the chip wasn't designed for FM radio. While I
>don't see any reason it shouldn't work, I don't know of anyone that's used
>this particular chip (CML CMX860) for packet before. Probably because it's
>not available in a DIP package, and it doesn't have a raw FSK output like
>the MX614 or TCM3105 - all host communication is through a programmed
>serial interface.
Beware of interface bugs. The few times we used anything other than a raw
output modem chip, we got hosed because of sneaky problems in how they
implemented the modem.. One other was because Rockwell started shipping
millions of chips that output the wrong answer tone. Our chips insisted on
getting the RIGHT answer tone for the mode, and they wouldn't allow us to
proceed without it. (Sometimes, even when you do it all correctly, you
STILL get hosed). Rockwell finally acknowleged the problem, but of course
refused to do anything about it. 212A, V.22BIS, and now 212Rockwell..
@%()%#(*&^
>It's also more expensive than the MX614, but it includes a DTMF decoder.
>Since I was planning to add a DTMF decoder anyway, this saves money, power,
>and board space. It's also got some programmable tone detector and
>generator features, but I'm not sure yet what I'll do with those.
Sounds interesting. I'll have to pull the data sheet later and check it out.
----------------------------------------------------------------------
Subject: Re: New tracker design suggestions
From: David VanHorn <dvanhorn@cedar.net>
Date: Mon, 29 Mar 2004 14:07:06 -0500
X-Message-Number: 25
At 10:38 AM 3/29/2004 -0800, Scott Miller wrote:
>>For my uses a headlamp or flashlight will suffice. I don't need the
>>backlight. For a mobile situation though I suppose you couldn't get
>>by without it.
>
>I think I'll just provide a standard 16-pin header and leave LCD selection
>up to the user. It'd be nice to have the backlight power under software
>control - that'll require a FET or something since I don't think any of the
>LED drive pins on the CPU can sink enough current for a backlight.
Fet's best. Even if the MPU will drive it, you'll have a lot of voltage
drop with any real current flowing.
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Subject: Re: New tracker design suggestions
From: Jeff King <jeff@aerodata.net>
Date: Mon, 29 Mar 2004 13:08:55 -0600 (CST)
X-Message-Number: 26
Quoting "Curt, WE7U" <archer@eskimo.com>:
>On Mon, 29 Mar 2004, David VanHorn wrote:
>
>>A NIMH pack, and switching regulators would be a huge improvement in
>any low-power project.
>Very much agreed! I have NiMH packs too, and actually would prefer
>to use those.
FYI, off the shelf D cell alkalines are *way* better then D cell NiMH. A D
cell alkaline has a AMP/Hour rating of 17, the NiMH has a rating of 7 amp
hours.
See:
http://rocky.digikey.com/WebLib/Panasonic/Web%20data/Panasonic_Alkaline_Hdbk_03-
04_v1.pdf
http://rocky.digikey.com/WebLib/Panasonic/Web%20data/HHR650D.pdf
----------------------------------------------------------------------
Subject: Re: New tracker design suggestions (fwd)
From: David VanHorn <dvanhorn@cedar.net>
Date: Mon, 29 Mar 2004 14:10:14 -0500
X-Message-Number: 27
At 10:54 AM 3/29/2004 -0800, Scott Miller wrote:
>>This would be good, but I want a tracker that has a separate port for
>>connection to a $50 Palm V or VII unit. I don't necessarily want the
>>tracker to see locations, but definitely want the tracker to be able to
>send
>>amessage from a list of preprepared feature messages.
>
>In the future, I'd like to provide Bluetooth support. Since some PDAs
>already work with Bluetooth GPS receivers, you could connect a hardwired GPS
>to the tracker and have it pass the NMEA data, along with injected
>waypoints, over Bluetooth. Ideally you'd run custom software on the PDA
>that'd let you draw search areas, plot DF bearings, and so on. Everything
>but the PDA would stay in your backpack, eliminating all of the cable
>clutter.
Zeevo Zerial modules work nicely.
You could do the chips, if you have BGA capability, otherwise, they offer a
module with the BGA mounted, and all the peripheral components. AT command
set, and it just looks like a serial port.
>The DB9's aren't a problem. Not sure about power. You could use the RJ45
>input, since it'll be wired to accept +8V from Kenwood mic connectors. I'd
>been planning on a simple coaxial plug, but those do tend to work loose.
>Running on an internal NiMH battery pack would eliminate that problem.
Dave's Connector Rule: "If it fits, it works, or at least it does no harm."
>A pushbutton-style power switch like the KPC-3's might also be a problem
>when it's shoved in a pack. I'll have to keep that in mind. Maybe a bypass
>jumper?
Mine Just fits in the ammo can, but if it got bounced around a lot the
switch might be pushed. Bypassing the switch is a real option. Not much
sense in turning it off anyway, it draws almost nothing with the LEDs off.
----------------------------------------------------------------------
Subject: Re: New tracker design suggestions
From: David VanHorn <dvanhorn@cedar.net>
Date: Mon, 29 Mar 2004 14:17:08 -0500
X-Message-Number: 28
>FYI, off the shelf D cell alkalines are *way* better then D cell NiMH. A D
>cell alkaline has a AMP/Hour rating of 17, the NiMH has a rating of 7 amp
>hours.
Of course, The alkaline is a primary cell. Secondary cells always have
lower capacity per volume and/or weight than comparable primaries.
Now what's the price of 12V worth of D cells?
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Subject: Re: New tracker design suggestions
From: "Curt, WE7U" <archer@eskimo.com>
Date: Mon, 29 Mar 2004 11:23:31 -0800 (PST)
X-Message-Number: 29
On Mon, 29 Mar 2004, Jeff King wrote:
>>Very much agreed! I have NiMH packs too, and actually would prefer
>>to use those.
>
>
>FYI, off the shelf D cell alkalines are *way* better then D cell NiMH. A D cell
>alkaline has a AMP/Hour rating of 17, the NiMH has a rating of 7 amp hours.
Good info. I'm not sure I'd want to carry around another set of D
batteries for a tracker. Already carry a set for my headlamp and
they weigh a ton. One of these days I'll have to invest in one of
the LED headlamps that run off AA's.
One of the objections some of the SAR members have had to the whole
idea of APRS trackers was the extra weight they'd have to carry.
These comments mostly come from our mountain rescue members, who
must carry rope/climbing gear and have learned to minimize their
equipment weight down to the last ounce.
Often these are the most important groups for us to track, as they
are sometimes bedded down on a glacier or snowfield, moving again at
3 or 4am while the surface is stable. Having a light APRS tracker
for them to carry would allow "mom" (base support group) to verify
their health through the wee hours of the morning. So... Weight is
important to us.
Even regular troops need to keep the weight down for those long
missions. We'd have a revolt if I asked one person from each team
to carry a tracker using a set of D's. AA's and a tracker I think I
can get away with.
--
Curt, WE7U archer at eskimo dot com
Arlington, WA, USA http://www.eskimo.com/~archer
"Lotto: A tax on people who are bad at math." -- unknown
"Windows: Microsoft's tax on computer illiterates." -- WE7U
"The world DOES revolve around me: I picked the coordinate system!"
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