From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from snark.thyrsus.com (static-71-162-243-5.phlapa.fios.verizon.net [71.162.243.5]) by huchra.bufferbloat.net (Postfix) with ESMTP id 23D3D2004D7 for ; Thu, 15 Mar 2012 04:06:02 -0700 (PDT) Received: by snark.thyrsus.com (Postfix, from userid 1000) id CD6C040617; Thu, 15 Mar 2012 07:05:40 -0400 (EDT) From: esr@thyrsus.com (Eric S. Raymond) To: thumbgps-devel@lists.bufferbloat.net Message-Id: <20120315110540.CD6C040617@snark.thyrsus.com> Date: Thu, 15 Mar 2012 07:05:40 -0400 (EDT) Subject: [Thumbgps-devel] Shotgunning the Shenzhen scene X-BeenThere: thumbgps-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 15 Mar 2012 11:06:02 -0000 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@mightygps.com (MightyGPS.com), service@sja.com.tw (Sheng Jay Automation Technologies Co.), sales@navisys.com.tw (NaviSys Technology Corp.), taylor.he8@gmail.com (Shenzhen Shanhai Technology), michael@chinaonwin.com (Shenzhen Onwin Enterprise Limited), dawn@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. -- Eric S. Raymond 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.