[Thumbgps-devel] Shotgunning the Shenzhen scene

[Eric S. Raymond]

I spent several hours last night mining alibaba.com for contacts at
mainland Chinese electronics manufacturers. They don't publish email
contact addresses, so you have to use their real-time chat facility to
scare up a trade rep and talk him or her into disgorging an email
contact address for your RFP.

Here's who I ended up sending the spec to:

info at mightygps.com (MightyGPS.com), 
service at sja.com.tw (Sheng Jay Automation Technologies Co.), 
sales at navisys.com.tw (NaviSys Technology Corp.),
taylor.he8 at gmail.com (Shenzhen Shanhai Technology),
michael at chinaonwin.com (Shenzhen Onwin Enterprise Limited),  
dawn at unitraq.com (UniTraq)

According to alibaba there are about a dozen Shenzhen and Taiwanese
companies shipping USB GPS dongles, but many of the product
descriptions and enclosures are so similar that I think these are
shells around no more than 2 or 3 distinct manufacturing and
engineering groups.  I'm pretty sure the list above covers all of
them.

Here's what I sent.  More comments below.

---------------------------------------------------------------------
I have a requirement for more than 100 USB GPS dongles.  I am
considering your company as a potential supplier.  I need a basic,
no-frills USB GPS in a thumb-drive-sized enclosure. Data logging and
other functions are not required, just location and time with 1PPS.

To evaluate the suitability of your product for my deployment, here
are some questions for which I need answers:

1. Please identify your eligible product by name and model number.

2. What GPS chipset does it use? (e.g. SiRF-III, Skytraq 6, etc.)

3. What USB-to-serial adapter does it use?  (e.g. PL23203, FTDI SIO, etc.)

4. Does your product carry the 1PPS timing signal from the GPS chip to
   to the DCD or RI input pin of the USB interface?

5. If the answer to question 4 is "no", would you be able to produce a variant
   that carries the 1PPS signal to the USB interface?

I am part of a group of engineers troubleshooting some wide-area
Internet performance problems. The deployment is for network delay
tomography, providing time service to monitoring routers running
Linux.  If you know of any specific feature of your product that might
impact this use, please specify.

If you are not familiar with "1PPS", it is a timing signal emitted
at the top of every GPS second to within 50 nanoseconds.  Almost all
GPS chipsets emit it to an output pin.  Many serial GPSes connect it
to the DCD or RI pin of an RS-232 interfaces.  I need a USB GPS that 
passes 1PPS state changes to the host as USB events.  If your dongle 
does not already do this, it is likely that adding a single trace to
your PCB (possibly with a level shifter) would add this capability.

If you did not find the above explanations understandable, please
forward this email to your product engineers.
---------------------------------------------------------------------

I see the following possible outcomes from this.  

1. One of these outfits is already manufacturing what we want and
   will tell us so.  Game over, we win.  I think this is unlikely,
   but it's possible.

2. None of these outfits are manufacturing what we want, but will 
   offer to OEM what we want once they figure out it's a single
   trace and a level shifter.  Probable win, depending on price.

3. Nobody will OEM what we want, but the information I elicit will
   identify plausible targets for devices to be blue-wired or 
   reverse-engineered.

Interesting note: The *only* trade rep who understood my query about
1PPS was at an outfit called Xucai Technologies that seems to be the 
actual manufacturer of the Chinavision dongle with the 8-pin PL2303
clone in it.  She told me they don't carry out the handshake signals, 
confirming our suspicions.
-- 
		<a href="http://www.catb.org/~esr/">Eric S. Raymond</a>

You [should] not examine legislation in the light of the benefits it will
convey if properly administered, but in the light of the wrongs it
would do and the harm it would cause if improperly administered
	-- Lyndon Johnson, former President of the U.S.