GPS GEN 3 TGW-3500

The information below on discontinued products is provided for individuals who are still using these older systems. Product descriptions may be time sensitive or even outdated. Please contact Telonics if you have questions.
A TGW-3500 shown on a collar with GPS antenna and a CR-2a collar release. The unit is shown with Cast 5 option where only the antenna exit point is cast with urethane to minimize the configuration's weight.

The TGW-3500 GPS Store on Board Unit is specifically designed for studies which require the collection storage of GPS latitude, longitude, and altitude. The TGW-3500 unit was designed for instrumentation of animals in the size class of deer, sheep, mountain lion, or wolf. The unit can be used on other species of wildlife in this size class as well. Although the basic unit remains the same many features of the data collection and the attachment design are optimized for specific species and we strongly recommend that the researcher contact our staff to discuss the details of the configurations available.

Programming Data Collection

Data including latitude, longitude and altitude as well as temperature and activity data can be collected on flexible preprogrammed schedules. The fix schedule can either be provided by the researcher to Telonics and thus be installed at the factory prior to delivery, or by the researcher using a utility called PCU-3 Parameter Configuration Utility, a TSC-1 Telonics Smart Cable, and an adapter CN006313-001 (procured as a separate items).
Please note that since we are utilizing satellites which cover the entire world and we ship units throughout the world, we utilize GPS or GMT time as a standard for specifying all programmed time related parameters thus avoiding issues such as daylight savings time versus standard time in local areas. Any time parameters provide to Telonics must be specified in GMT (not local time).

An option exists that permits the user to differential correct the GPS data collected by the system for researchers who require additional accuracy in their systems. Note: Since the removal of Selective Availability in 2000, many researchers have been able to use the uncorrected GPS positions without need for the enhanced accuracy associated with differential correction. Some studies however, require all the accuracy possible and Option DC-1 allows the user to collect and store all the data necessary to post process GPS data after downloading. The DC-1 option must be purchased for each unit where differential correction is required. In addition to the DC-1 option, the user must make arrangements to acquire the appropriate GPS base station files for post processing. A utility program called DCU-1 used in conjunction with a Trimble program called Pathfinder Office allows the user to integrate the differentially correctable data with the appropriate base station files (acquired separately) and calculate differentially corrected GPS positions. Even under the best conditions not all positions can be differentially corrected.

Examples of the number GPS fixes which can be attempted versus the operational life of the system:

GPS Locations/Day Operational Life
Number of Stored Positions
5 742 3710
8 491 3928
12 338 4056
24 175 4200

Operational life estimates provided above are based upon the assumption that the time required for the GPS unit to fix position is 90 seconds. The estimates are based on battery performance at 25° C. The battery capacity should be further derated for continuous operation at a temperature of -40° C.

Sensor Data for SOB Systems

Activity Sensing Option

Option TACT-1 measures transitional events based on a motion sensitive switch installed inside the GPS unit. The user is able to specify a data collection interval. The data collection interval is initiated at the same time as the initiation of the each GPS Fix attempt. In this option the number of seconds during which a switch closure is detected are accumulated during the user specified data collection interval. The actual number returned is a percentage of the total number of seconds in the entire collection interval during which a switch closure event occurred. The resolution is 0.5% of the total data collection interval. This type of information is more useful if the researcher is interested in transitional information such as the number of times an animal lowers its head to feed during the data collection interval.

Exact rules and limitations for setting the data collection interval are described in the Telonics GEN 3 GPS System User's Manual.

Temperature Sensor Option

Option TEMP-1 measures the temperature inside the unit over the temperature range of -55° to +125° C. The resolution is 1° C.

Please consult the factory for details in optimizing data collection.

Downloading Units

Units can be downloaded by the researcher using the utility DU-3, the TSC-1 Telonics Smart Cable, and an adapter CN006313-001.

It is important to note that all memories used to store data on board the system are totally nonvolatile and do not require any battery backup ensuring that the data are secure even after years of storage.


  • Canister Measurement: 2.9 x 2.3 x 2.0 inches (7.4 X 5.8 X 5.1 cm).
  • Canister Weight: Approximately 405 grams (this does not include the weight of a collar or protective casting). Please note that when attaching the canister to a collar, a bracket must be placed on the canister. The standard orientation of the bracket is to the 2.3 X 2.9 inch surface.
  • Collar Configuration Options: GPS collars must be custom configured to the study species. The neck circumference adjustment range must be specified to +/- 2.0 inches to assure optimum positioning of the hardened GPS antenna on the dorsal side of the neck. The collar width is also an option that is tailored to the study animal and must be specified by the researcher.
    As an example, this completed unit configured with a GPS antenna and mounted on a 2.25-inch wide butyl belting collar with an adjustment range of 14 to 18 inches would weigh approximately 750 grams This weight includes the weight of 1 piece of #1 collar attachment hardware and end cast of urethane polymer (Cast 5 Option).
  • Protective Casting Options: For all GPS applications, it is a standard and advisable to cast either the antenna end of the transmitter housing (CAST-5) or the entire housing (CAST-4) in a high-density polymer that acts as a shock absorber. The full cast can add 60 grams of additional weight to the total system depending on the configuration. Note: All systems are hermetically sealed in the metal canister and the role of the polymeric cast is exclusively to act as a shock absorber not as a waterproofing agent.
  • Storage and Operational Temperature Range: -40° to 70° C
A TGW-3500 shown on a collar with Cast 4 option. The additional urethane aids as a shock buffer.

VHF Locator Beacon Options

The VHF transmitter performs several functions in the TGW-3500 store on board system:

  1. The unit can be monitored in the same way as other VHF transmitters during the course of the study. The animal wearing the collar can be relocated as required by the study design of the project.
  2. The unit provides insight into the performance of the GPS system's success throughout the course of the study. All SOB units are equipped with Option 400 GPS Last Fix Status. Using this option, the VHF transmitter provides one of two pulse periods. The distinctive pulse periods report to the researcher on the success or failure of the last attempted GPS position.
  3. The unit can be used to provide mortality sensing of the instrumented animal. MS6 Mortality Sensor is optional on all systems. A special pulse rate indicates that the unit has been inactive for a period exceeding (a user preselected time interval) mortality time out period.
  4. The VHF beacon allows the researcher to recover the collar after the data collection period or if the collar is released from the animal using a device like the CR-2a Programmable Collar Release.
  5. The VHF signal is monitored to assure that proper initialization of the GPS system has occurred at start of the system operation.

The VHF portion of the system is critically important to the SOB system and therefore care must be exercised to assure adequate operational life of the beacon. As an example, the VHF unit can be programmed to transmit pulses at a rate of 60 BPM or beats per minute (PP (pulse period) = 1000msec) when the system is on a living animal and the last GPS fix attempt was successful. The unit can be programmed to transmit pulses at 50 BPM (1200 msec) when on a living animal and the last attempt at a GPS fix was unsuccessful. The unit can be programmed to transmit pulses at 75 BPM (800sec.) when the animal has been inactive for a prolonged interval or is dead. Each pulse rate uses the battery capacity at a different rate and thus the operational life of the beacon is a direct function of the beacon pulse rate. Batteries are also affected by the environmental temperature during operation of the system. Most battery electrochemical systems provide less capacity at colder temperatures.

In the TGW-3500 configuration this corresponds to the following:

  • 60 BPM = 735 days of operational life at 25° C, 565 days at -20° C and 390 days at -40° C
  • 50 BPM = 870 days at 25° C, 665 days at -20° C, an 462 days at -40° C
  • 75 BPM = 602 days at 25° C, 460 days at -20° C, 318 days at -40° C

In the real world application the VHF transmitter and its battery may spend time at different pulse rates and at different ambient temperatures. The actual achieved operational life of the VHF beacon will be determined by the sum of all these factors.

The staff at Telonics will help you design the proper regime for your specific study conditions and species. As an example, we often recommend slower pulse rates for the inactive period for species which undergo a torpor or hibernate. This approach helps extend battery life when the animal is inactive and generally immobile.

An additional technique for extending the battery life of the system is to use a Duty Cycle for the VHF transmitter. This approach can be used to turn the VHF transmitter OFF at night if no monitoring is to be done during this period. Alternatively, the VHF unit could be turned off on the weekends and operate only during the week. Flexible duty cycles are available using the Option MDC Duty Cycles. Transmitters can be programmed to cycle through up to eight periods in order to extend battery life. Within each period, the transmitter can either be "on" or "off". Pulse rates can be uniquely defined for each "on" period. Each period can be defined from eight seconds to approximately 50 days in length.

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Additional Links & Information

For more information on the GEN 3 Store-on-Board Configurations, contact

Service Commitment

Since 1970, Telonics has built a reputation based on product quality, product support, service, and customer satisfaction. Telonics strives to produce the highest quality products, and to support those products accordingly.

Because of extreme conditions and the unpredictable nature associated with most telemetry applications, problems occasionally arise. Most problems can be resolved quickly. In all cases, we hope to be able to work in partnership with users to resolve problems to the user's satisfaction and to uphold our demonstrated commitment to excellence. If problems should arise, all products must be returned to our factory for failure analysis.


Telonics warrants its products to be free from defects in material and workmanship for a period of one year from the date acquired. Telonics does not warrant batteries.

If a defect occurs, return the equipment to us within the proper time frame at the following address: TELONICS, 932 E. IMPALA AVENUE, MESA AZ USA 85204-6699. Damage to any equipment resulting from misuse, accidents, unauthorized service, extreme conditions, or other causes, is excluded from this warranty. Telonics does not assume responsibility for loss or damage to equipment during shipment. Telonics does not assume responsibility for delays resulting from shipment on commercial or private carriers. We insure all equipment shipped from our facility and suggest that shipments to Telonics also be insured.

Upon the timely return to our facility, if defective, the product will be replaced or repaired at our discretion at no cost to the customer. This remedy is the exclusive remedy. This product is supplied without any further warranties or conditions, expressed or implied, including warranties of merchantability, quality or fitness for particular reason or those arising by laws, statutes or trade usage or course of dealing.

The entire risk, as to the results and performance of the product, is assumed by the customer. Neither Telonics, nor its suppliers, shall have any liability to the customer or any other person or entity for any indirect, incidental, special, or consequential damage whatsoever, regardless whether Telonics has been told of the possibility of such damages or that such damages might be foreseeable. Telonics has no responsibility or liability for the claims of any third party. The maximum aggregate to the customer, of Telonics and its suppliers, shall not exceed the amount paid by the customer for the product.