Comparison of Automatic telemetry equipment

William W. Cochran

Document dates:
original: Jan 15, 2002, preliminary descriptions.

ARU_02 is a redesign of the ARU_91 (Automatic Recording Unit). The ARU_91 (see Larkin, R. P., A. Raim, and R. H. Diehl. 1996. Performance of a non-rotating direction-finder for automatic radio tracking. J. Field Ornithol., 67(1):59-71. for description) was used in various studies from 1990 to 2000. ARU_91 refers to a succession modifications and additions made over the 1990-99 period, thus some descriptions, for instance Memory Modules, do not apply to the whole period. Functionally, however, ARU_91 represents a particular hardware design to which minor changes were applied. For examples of data from ARU_91 use, see sample data (there will be a link to these soon).

The ARU_02, manufactured by Sparrow Systems and Avondale Instruments, will be available in summer 2002.


DIFFERENCES (BETWEEN ARU_91 AND ARU_02)
  ARU_91 ARU_02
Freq coverage
   example:
# animals, 10 KHz spacing		 1 MHz (any band)
164 to 165 MHz
100		 21 MHz (any band)
148 to 169 MHz
2100
Power Supply 11 to 18 V @ 45 ma 6 to 18 V @ 35 ma
12-14 V @ 20 ma (option)
Hours of operation:
 with battery:		 155
Power Sonic 12 V 7 amp-hr
Model PS-1270  wgt 1400 g		 315
CSB 6 V 11 amp-hr
Model GP6110 wgt 800 g
Max # antennas varied: 5 to 8 8
Size 8 x 9 x 12 inches 5 x 5 x 5 inches
Sensitivity to detect presence-absence (DF limited to best antenna)
 pulsed transmitters (15 ms)
 continuous transmitters		 -140 dBm
-140 dBm		 -142 dBm
-144 dBm
Sensitivity for nearest 5-degree DF
 pulsed transmitters (15 ms)
 continuous transmitters		 -130 dBm
-130 dBm		 -132 dBm
-134 dBm
Multiple Antenna Arrays and type of DF
Switched antenna operation yes, 1 array yes, up to 3 arrays
Rotating Antennas no yes, up to 3 arrays
For comparison of Switched and Rotated, see Cochran, W. W., G. W. Swenson Jr., and L. L. Pater. Radio Direction-finding for Wildlife Research. http://userweb.springnet1.com/sparrow/Direction-finding.html.



NO DIFFERENCE (ARU_91 and ARU_02)
Max on-board data storage
 example: storage capacity
 for 15 animals per minute
 continous DF information		 8 Megabyte (Memory Module = MM)
 115 days
On-board calendar-clock <1 sec per month drift

Stand-alone operation supported as follows:

Memory Modules (MMs) are used to retrieve data from ARUs and provide set-up information to ARUs by connection of MMs to a standard PC parallel port. Set-up information includes frequencies to be monitored, type of data to be collected, data collection rate. The ARU may remain in the field because MMs can be exchanged periodically. The clock (date-time) is set by an PC-to-ARU serial port connection. Data stream out the serial port when a connection to a PC is detected, allowing monitoring the data as it is collected, if and when desired.

Transmitter types serviced:

Continuous, pulsed, simple pulse-interval and/or pulse-width coded, bit-word pulse codes (containing information derived on-animal, such as GPS position, activity, etc).

OPERATING MODES TRIED PRIOR TO 2000

Several system configurations of ARUs have been used. All will be supported by the ARU_02  (some will require hardware and firmware options).

  1. 1982 (pre-ARU_91) control and data access for 3 ARU's located on mountains and in desert was by telephone modems. Operation was similar to that described above for Memory Modules except that data storage limitations required servicing daily.

  2. TRACER (http://userweb.springnet1.com/sparrow/TRACER) used pre-ARU_91s in an 8-tower real-time system via radio control and data access (in todays terminology ... wireless). Data streamed continuously from the 8 remotes to a PC (8 MHz IBM PC-AT) that plotted fixes and stored the data.

  3. The first ARU_91s were used in 2-(1990) and 3-(1992-93) tower systems for Illinois Natural History Survey animal tracking projects. Control was by wireless. Three modes of operation were used. (1) In stand-alone operation the ARU's collected data as per instructions sent them by wireless. Once daily, data files were retrieved, again by wireless, and new instructions, if any, were sent to the ARUs before they were again put in collect-data mode. (2) In slave mode the ARUs were linked by wireless to the central PC. The PC issued instructions in small batches (such as DF on animal 328), whereupon the ARUs would do so, send the data, and wait for the next PC command. (3) portable stand-alone ARUs were routinely taken to monitor specific animals not within range of the towers. For these, the antenna was on a 3-m mast. Data were retrieved by laptop connection to serial port at least daily (due to memory storage limitations).

  4. In 1996 ARUs gathered "activity" data for a UI ECE dept. project (sponsored by U.S. Army Corps of Engineers). Operation and equipment were as in 3(1) above except that the ARUs streamed the data (by wireless) to the central PC continuously. The central PC displayed and filed the data.

  5. In 1997 a continuation of the 1996 project included DFing from 4 ARUs, again with data streamed to the central PC as in 3 and 4 above.

  6. In 1999 and 2000 activity data were gathered with portable stand-alone ARUs as in 3(3) above, with the difference that Memory Modules were first used. These relieved the necessity of daily visits to download data and allowed storage of more data per animal (signal and pulse interval) because storage memory was essentially unlimited.

Maintained by : William W. Cochran
Last modified : Wednesday, January 9, 2002