GPS: GPS receiver testing – Garmin GPSMap 60CSx

[Bryan]

I have been doing some real-world testing of my GPS receiver, a Garmin GPSMap 60CSx, to prepare for my upcoming trip to China. The tests are in these categories:

• Track intervals, sizes, and capacity
• Battery life
• Positional accuracy, sensitivity and reception

Before doing any tests, I made sure that my receiver had the latest firmware, version 3.60, dated 18 February 2008.

[Bryan]

The 60CSx offers track logging frequency by time, distance, or in automatic mode. The automatic mode frequencies are calculated based on the change of time, position, and direction (heading). Five frequency options are available. I tested all of them and found these results:

Most often setting: 5.1 seconds average interval
More often setting: 6.6 seconds average interval
Normal setting: 7.5 seconds average interval
Less often setting: 8.4 seconds average interval
Least often setting: 9.4 seconds average interval

These results were obtained by logging a combination of about 75% running and 25% walking for four laps around a 0.5-kilometer (about 0.3-mile) track. Hiking would be slower so the frequency would be somewhat less.

The Least often setting would provide more than enough detail. The receiver will hold a maximum of 10,000 track points in memory. Logging at a 10-second interval for 24 hours would produce 8640 points, and since I will be saving the track log to the SD card, and I won’t be logging for 24 hours per day, the maximum track size should be no problem.

The track files used about one kilobyte for each 8.5 points, so 24 hours of logging at 10-second intervals would take about 1 megabyte. Since I have a 2 gigabyte SD card and I expect to use less than half of its capacity for maps, storage space will not be an issue.

[Bryan]

I tested the life expectancy of Energizer Lithium disposable batteries because they should last longer than any other available battery. They are also lighter weight than alkaline batteries. One AA alkaline battery is 23.7 grams and the lithium is 14.5 grams.

I tested with backlight off, compass off, WAAS off, and battery saver mode off. I tested indoors at about 20°C (about 70°F). I simulated real world usage by changing screens periodically and turning the power off about every 6 to 8 hours. While on, the GPS was logging its track position once every 30 seconds for my first test, and once every second for the second test. The batteries lasted for 40.75 hours in the first test, and 39.75 hours in the second test. This is more than double the usual 18 hours reported for alkaline batteries.

The battery meter did not go from four bars down to three bars until about 35 minutes before all power was lost. Two bars showed at 12 minutes remaining, and one bar showed at 9 minutes remaining. 0 bars showed and the warning beep and message were issued with 6 minutes remaining. These results were observed with the battery selection set to “alkaline”.

Since disposable lithium batteries cost more than twice the price of alkaline batteries, they are not cost effective from a pure time vs. money perspective. But in addition to the convenience of less frequent battery changes, and the slight space savings, the weight savings is very significant. A quick weight calculation for enough batteries to run for 160 hours: 8 lithium batteries at 14.5 grams (0.51 oz) = 116 grams (4.08 oz) vs. 18 alkaline batteries at 23.7 grams (0.84 oz) = 426.6 grams (15.12 oz). The total battery weight factor is about 3.7:1. That’s a huge weight savings when you need to carry enough batteries to last over a month!

Incidentally, rechargeable batteries are a good alternative, but not for long hikes, when one never knows when electricity will be available.

[Bryan]

I tested by leaving the receiver in one place for one hour after resetting the track log and trip computer. I tested with WAAS off and battery saver mode off. These are the results:

Indoor stability test

Reported accuracy: ± 28 feet
Reported moving time: 9 minutes
Reported distance: 12.5 meters (41 feet)

Outdoor stability test in an open area in cloudy weather

Reported accuracy: ± 15 feet
Reported moving time: 0 minutes
Reported distance: 0 meters (0 feet)

Outdoor stability test in an open area in cloudy weather – inside backpack

Reported accuracy: ± 15 feet
Reported moving time: 2 seconds
Reported distance: 1.22 meters (4 feet)

Comparative reported accuracy test

Nüvi 350 compared with 60CSx – 33 feet vs. 15 feet accuracy
6 satellites for Nüvi 350 compared with 8 for 60CSx
Measured in open field under cloudy sky
(Also note the Nüvi screen is less clear due to being a touch screen)

Sensitivity and reception

I tested by setting the receiver to log the track position every 10 seconds. I packed my backpack (a Golite Jam2) with a representative load and placed the receiver inside the backpack with the antenna pointed up. I went for a ten-minute hike in a semi-wooded area on a cloudy day. The receiver was not impeded by being enclosed in the pack, but was able to record its position every 10 seconds. I repeated the exact same hike with the receiver attached to the shoulder strap of the pack, with the antenna pointed up, and overlaid the two tracks on the map. They matched perfectly. Due to this result and the results of the positional accuracy tests above, I concluded that reception and accuracy are not degraded significantly by keeping the receiver inside my pack. This performance was very impressive to me.

[Bryan]

Saving automatically and manually

For this test, I set the receiver to log tracks to the data card on the Data Card Setup page from the Tracks Setup page. I found that if you do not save the track log manually via the menu, the track log is saved every day automatically. These tracks do not show on the list of Saved Tracks on the Tracks page, but they do show under Data Card Tracks on the Data Card Setup page. They can be copied from the data card in USB Mass Storage mode.

Exceeding the 10,000 point limit

For this test I enabled the option for Wrap When Full on the Tracks Setup page. If the track log exceeds 10,000 points, all of the points from the beginning to the end of the track are saved to the track log, even those that are beyond 10,000 points. Logging for 24 hours at a 1 point per second interval produced a 9.63 megabyte file with 86,319 points!

Power out while logging

For this test, I set the receiver to log tracks to the data card on the Data Card Setup page from the Tracks Setup page. I left the receiver logging every one second while the batteries became depleted. If battery power is lost while logging the track, the track log file on the memory card is closed cleanly at the last moment.

Logging over midnight

For this test, I set the receiver to log tracks to the data card on the Data Card Setup page from the Tracks Setup page. I used a logging interval of one second. When the track log is operated over midnight, the file is saved automatically with a final time stamp of 23:59:59 (local time) and a new file is started for the next day with a starting time stamp of 00:00:00 (local time).

[lsanderson]

Bryan you did a great job on these tests. I learned a lot by reading them. Thank you for posting your results. I agree with you about the lithium batteries. I think their performance is worth the price.

[Bryan]

Originally Posted by lsanderson

Bryan you did a great job on these tests. I learned a lot by reading them. Thank you for posting your results. I agree with you about the lithium batteries. I think their performance is worth the price.

Thanks! It was fun.

[Kim]

Very impressive testing of the 60CSx

It seems to be a very good choice for long hikes especially with the lithium batteries - very impressive that they last about 40 hours.

I will order one in Denmark when I go home for vacation in the summer.

[Bryan]

Originally Posted by Kim

Very impressive testing of the 60CSx

It seems to be a very good choice for long hikes especially with the lithium batteries - very impressive that they last about 40 hours.

I will order one in Denmark when I go home for vacation in the summer.

You may want to compare prices and consider getting one in China since the Unistong versions come with the China City Navigator 6.0 maps.

[Kim]

You may want to compare prices and consider getting one in China since the Unistong versions come with the China City Navigator 6.0 maps.

It's cheaper to buy it in Denmark and I already have a Nüvi 300 with China City Navigator Eng v. 5.51 and that map is not very useful when it comes to hiking. I will update the map after the Olympics to get the latest roads but I don't expect that the amount of details outside the bigger cities have been improved - certainly not for hiking.