First Statement

From: dkabel@microlink.net (Darrin Kabel)
Newsgroups: sci.geo.satellite-nav
Subject: Setting the record straight on Garmin's test mode.
Date: Wed, 07 May 97 22:33:41 GMT
Organization: MicroLink Net, Kansas City, MO

As a software engineer for Garmin, I can't go into the details of how test mode works, or why you should or shouldn't use the unit in this fashion. All I can say is that the unit was never intended to be used in either test mode or diagnostics mode for satellite tracking or navigation. These modes are for our use in product development, factory testing, and problem troubleshooting.

We are not, however, stupid. We know that users such as many who frequent this group will find and use test mode and diagnostics mode. Therefore, I assure you that we would never intentionally put anything in our hardware or firmware that would render a unit un-usable, in any mode of operation.

A good rule of thumb is to always use our products the way they were intended. If however, you accidentally get the unit into test mode and it tracks satellites before you can shut it off, don't worry. It won't damage the unit and it should work fine the next time you power it up normally.

We want everyone who uses our products to have fun with them. Relax and enjoy them! We certainly enjoy making them for you :)

Thanks,

Darrin Kabel
Garmin Software Engineer

Further clarification

From: dkabel@microlink.net (Darrin Kabel)
Newsgroups: sci.geo.satellite-nav
Subject: Re: Setting the record straight on Garmin's test mode.
Date: Fri, 09 May 97 22:52:41 GMT
Organization: MicroLink Net, Kansas City, MO

skeeter@nospam.usask.ca (Skeeter Abell-Smith) wrote:
snip
>Thanks _very_ much for the reassurance.  I feel better now, but I am
>also somewhat confused.  An earlier post (which can be found at
>http://www.bridge.de/~tom/garstatm.htm) stated in part "You are asking
>people to destroy the SCXO compensation curve in their units, which may
>render them useless."  It was also written by a Garmin person, Bill
>Stone.  Should we take your word overy his because you are a Garmin
>Software Engineer and Mt Stone's just a Product Support Manager?  =-]
>
snip

Bill Stone's comments were not completely incorrect. The technical information he gave was very accurate. Much to his credit, he is a very knowledgable product support manager and a tremendous asset to Garmin. I think the problem is that we in Garmin engineering have not done a good enough job in communicating with our customer service people concerning the consquences of tracking real satellites in test mode. I've been given permission to explain with more detail.

First of all, let's make sure we're all on the same sheet of music. Test mode is the operating mode that shows you a page with SNR, DRIFT, FREQ, and other things. It's different for each of our products so that's about as much detail as I can offer. Diagnostic mode, on the other hand, looks just like normal mode except a few surprise pieces of information pop up in places :)

In test mode, the unit may track the live orbiting satellite equivalent of our artificial lab calibration satellite, and if it does, it will assume no doppler shift for it. This could cause a small error in the unit's perception of it's crystal frequency for the current temperature. The maximum error will be incurred when the satellite is low on the horizon and moving directly toward or away from you. Any other condition will result in less error. The only negative impact you may observe is a longer aquisition when you shut down test mode and power back up normally. Given the small statistical likelihood of the maximum error conditions, the increase in normal acquisition time will usually not be significant. If you ever feel that acquisition is taking much too long and you've been tracking in test mode since the last time you tracked normally, you can simply select the unit's AutoLocate feature and it will ignore the erroneous crystal frequency compensation. Your user's manual will tell you how to select AutoLocate. Once you acquire satellites in the normal operating mode, either by waiting through a longer acquisition or by using AutoLocate, the unit will continue its process of "re-learning" its compensation table. Any errors that may have been recorded in test mode will be corrected as the unit continually adapts to its age and environment. Operation will then be completely normal. No repair technician needed :)

In diagnostic mode, the unit tracks satellites just like it does in normal mode. There are no negative impacts to the receiver's performance after being in diagnostic mode.

I hope this settles the issue once and for all. Before I leave you kind people in peace, I must add once again that these "extra" modes are not intended for normal use. Please avoid intentional use of the product in these fashions. But don't worry if it happens accidentally. You shouldn't have to send it to us for repair.

In closing, let me say THANK YOU to all of you in this group for working through this issue with us. Your diligence in pointing out our inconsistencies will help us to improve our internal communication and provide you with better service and information. We appreciate it! Also, I'm not posting these comments in any official capacity with Garmin. I'm doing this on my own time because I want to. Please don't be offended if I can't answer a question or if I don't immediately respond to your email. If you need an immediate answer, please contact our customer support. If you have a "just curious" question, post it here and I'll answer if I can. As you can imagine, my email has become quite popular since I admitted to being a Garmin engineer :) Please use this news group for posting questions or comments if you can. But if you think a post could result in flaming or critical comments from the less genteel, go ahead and email me.

Thanks again, and happy tracking!

Darrin Kabel