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Lotek Wireless SRX 400, User Manual

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Lotek Wireless SRX 400 User Manual Download Page 26

Rev B 

 

26 

 

  
 Here the system response is slower, and detectability of repetition coded  
transmitters (with their obligatory longer group size) is  especially poor. What is 
happening is that so many noise events  are being interpreted as impulses (i.e., 
ignored) that the local  gain reduction algorithm has failed to reduce the gain  
sufficiently to clear away the other (non-impulsive) noise  components. 
      Disabling the noise blanking algorithm altogether had this  effect: 
  

 10/11/89  14:45:11 151.450*64*78 151.138*96*107  

 10/11/89  14:46:03 151.450*64*92 151.138*96*91  

 10/11/89  14:47:03 151.149*2R*183  

 10/11/89  14:48:34 151.450*63*71 151.138*96*79 151.149*2R*164  

  
 Again system performance is slow, and the 3 beater at 151.158 is  not detected at all, 
this time because the strong interference could not be sufficiently suppressed by 
gain reduction methods  alone. 
      With the noise blank level = 64, 
  

 10/11/89  14:51:15 151.450*64*90 151.138*97*98 151.149*2R*178 

151.158*3R*96  

 10/11/89  14:52:07 151.450*64*101  

 10/11/89  14:53:05 151.149*2R*173 151.450*64*82 151.138*97*77  

 10/11/89  14:54:09 151.149*2R*186  

 10/11/89  14:55:14 151.450*64*98 151.138*83*75 151.158*3R*82  

  
      the 3 beater is back. Trying blank level = 54, 
  

 10/11/89  15:01:05 151.149*2R*169 151.158*3R*135 151.450*58*102 

151.138*96*87  

 10/11/89  15:02:05 151.149*2R*173 151.450*64*95 151.138*96*98  

 10/11/89  15:03:03 151.149*2R*164 151.158*3R*132 151.450*64*66  

 10/11/89  15:04:25 151.450*64*89 151.138*96*84 151.149*2R*172 

151.158*3R*80  

 10/11/89  15:05:04 151.450*64*88 151.138*96*92 151.149*2R*175  

 10/11/89  15:06:08 151.158*3R*120 151.450*64*79 151.138*96*78 

151.149*2R*189  

  
 This is quite good performance for the conditions.   
      On the assumption that starting with a lower baseline gain should speed up 
acquisition we next tried setting the global noise threshold so that the system would 
settle at a lower gain.   In this case the target was 56, the highest gain without noise  
triggering in 

SIGNAL

/Interval

.  Because the noise blanker is  working, we must 

expect to set the global noise threshold fairly low (since noise rejected by the noise 
blanker is not logged, and therefore not counted by the gain reduction algorithm). 
      Trying a value of 4, the gain settled at 58, giving 
  

 10/11/89  15:34:06 151.450*66*120  

 10/11/89  15:35:10 151.149*2R*172 151.158*3R*127 151.450*64*87 

151.138*96*93  

 10/11/89  15:36:05 151.149*2R*163 151.158*3R*97  

 10/11/89  15:37:11 151.450*64*103 151.138*96*79 151.149*2R*181  

 10/11/89  15:38:14 151.450*64*103 151.138*96*85 151.149*2R*172 

151.158*3R*123  

  

Summary of Contents for SRX 400

Page 1: ...LOTEK Wireless Inc Newmarket Ontario Canada E00033 Rev A Rev B ECO 302 31 Mar 2001 SRX_400 TELEMETRY RECEIVER USER S MANUAL Version 4 xx Deleted 3 6x ...

Page 2: ...IGNAL 10 SCAN 11 FTABLE 13 TIME 14 COMM 14 CODE 15 F0 F3 16 Panel Light Switch 16 Hardware Reset 16 SRX_400 OPERATIONS AND EXERCISES 17 Preface to the Examples 17 Example 1 Tracking 17 Example 2 Optimization 22 ADAPTIVE GAIN CONTROL 23 OPTIMIZING NOISE PERFORMANCE IN EVENT_LOG 24 Example 3 Automated Data Collection 27 REMOTE OPERATION BY TELEPHONE 28 APPENDIX A RS232 PORT CONNECTOR AND NULL MODEM ...

Page 3: ...ns offer selective switching of up to 8 antennas and provide up to 1Mbyte of additional memory for data storage This manual describes the basic operating functions of the SRX_400 common to all software versions as well as a number of support services available as options Some of these services like serial communications support cooperate with or are required by any of several high level applicatio...

Page 4: ...ed for RS232 communications dumps terminal control DSP 9 pin SERIAL II serial port used for DSP_500 interface in versions supporting both DSP and terminal communications 9 pin The SRX_400 receiver will operate continuously for about 12 hours panel light on or 16 hours light off on a fully charged C battery pack The receiver operates on C or D type rechargeable nickel cadmium NiCad batteries Panaso...

Page 5: ...re the receiver for extended periods e g over winter it is recommended that you charge the battery once a month to conserve memory backup power see below and to avoid possible impairment of the battery s energy capacity and overall life To minimize memory effects the best procedure is to run the receiver until the low battery symbol appears when the SHIFT key is pressed and then charge until the t...

Page 6: ...d by the operating system are likewise indestructible since they are reinitialized on startup All other memory including user specified parameters like frequency tables and gain settings and also the time and date are saved in battery backed up RAM Back up power is supplied by the main batteries as long as they have sufficient charge and by an on board lithium battery which will provide memory pro...

Page 7: ...ll keys except SHIFT have dual markings The upper markings above the line represent SHIFTed functions or commands The lower markings include some commands but mostly they are reserved for the numeric digits 0 to 9 and the decimal point Any key can therefore be referred to by two names depending on which key function is being selected This convention is used in the discussion below Numeric values a...

Page 8: ...t issues a prompt and then waits until it receives input from the keypad in the form of a 6 digit decimal number 5 digits in 30 70 MHz versions representing the receive frequency in MHz megahertz It then sets the receive frequency by programming the frequency synthesizer If the requested frequency is out of range of the hardware it may depending on the receiver configuration be automatically limit...

Page 9: ... not a substitute for the operating manual In order to conserve program memory HELP is not provided in advanced software versions The SEARCH key provides access to several functions Its menu is The search functions scan through a range of frequencies looking for a signal using the frequency increment set by the SET operation If an active signal is found at any frequency the routine continues scann...

Page 10: ...al does not exercise any automatic control of receiver gain In a noisy environment e g in an aircraft or in the vicinity of computer equipment it is possible to set the gain high enough so that the receiver is saturated with noise and cannot detect even a reasonably strong signal Simply reducing the gain will normally correct this situation See also the Optimization example in section II of this m...

Page 11: ...nd increments ESC exits Boundaries allows you to specify a time window in milliseconds for valid pulses Enter boundary values as 5 digit numbers including leading zeros if necessary If you don t want any time interval filtering open the window by setting the boundary values far apart e g upper bound 10000 and lower bound 00001 Whatever values you set for the window will be remembered by the receiv...

Page 12: ... indicate the last operation performed Restoration is applied on a last out first in basis only to frequencies which have been previously deleted Frequencies which have been deleted but not restored at the end of a scanning session may be restored en masse using the FTABLE Copy function see below The SHIFT F2 key sequence calls a scratch pad routine for manual entry of mercator coordinates environ...

Page 13: ...View and allows scrolling through the frequency table using the arrow keys Copy causes all frequencies which have been deleted but not restored while scanning to be written back into the active partition Frequencies deleted by the FTABLE Delete command cannot be recalled in this way but must be re entered using Add Some SRX_400 software versions provide a facility for uploading frequency tables fr...

Page 14: ...t file if desired Host Press 7 for the utility Upload F Table to SRX you will see a list of files in the data directory Host Highlight your file and press ENTER SRX Select Upload table from Host routine SHIFT FTABLE SRX Press 1 On completion of the upload operation the SRX_400 will notify you by displaying the number of frequencies loaded and or a diagnostic message The TIME key gives a display of...

Page 15: ... command set selecting auto answer mode initializes the modem to its power up defaults and sends the current SRX_400 communication settings The modem will enable its auto answer feature on some modems an LED AA indicator will light up which means it will answer all incoming calls and negotiate a data link with the calling modem The SRX_400 also asserts its own auto answer state which will cause it...

Page 16: ... for scratchpad data entry in the SCAN routine The F1 key accesses the system initialization functions These include the New Prom routine which resets the value of all system variables to their factory default values and optionally purges scan tables and data storage Access to this routine is restricted by the pass code The F0 key calls Event_Log Code_Log Temp_Monitor or other application programs...

Page 17: ...e your receiver is scanning through a largely inactive list as low as possible You recognize however that in order not to bias your experiment you will need an efficient procedure for finding animals which have jumped islands so you have reserved a partition also for the complete list one for a combination of the lists from islands 1 and 2 which are close together and one for a combination of the ...

Page 18: ...c NOTE All digits must be entered After the last digit is entered the receiver will automatically return to the command environment display frequency and gain with the addition of scan time in the lower left quadrant The arrow keys will now adjust the scan time using the time increment selected by the SET function Since you will be flying you will be concerned about the levels of noise generated b...

Page 19: ...rform a SET G operation You may do this without specifying any new value of gain Press SHIFT SET G ESC Arrow keys and SET now control gain Now press SHIFT SET and enter the two digit gain increment value e g 01 Returning to the SIGNAL Interval routine you continue to increase the gain until you begin to see random triggering of the signal strobe character lower right display quadrant For automatic...

Page 20: ...g the signal strobe active If you are using a set of isolating headphones you will be able to hear very weak transmitters before the receiver does see Example 2 Optimization below You may wish to turn the aircraft in the direction of the strongest signal to obtain a more accurate position estimate in which case you can stop the scan by pressing the decimal point key If the program has already scan...

Page 21: ...ssion from the command environment press SHIFT F TABLE and then 3 Copy All frequencies which have been removed during SCAN will be restored and the program will report the number of frequencies copied If you are using more than one partition table you will have to repeat this operation for each one individually To change the partition from the F TABLE menu select item 4 Partition and enter a two d...

Page 22: ...mended that you use a filtered RS232 cable Special cables and connectors are available for this purpose or a standard cable may be coiled around a ferrite core Contact Lotek for more information Finally it is a good idea to perform some initial experiments to determine the noise floors and if possible the dominant noise types in your study area s Although data acquisition programs like Event_Log a...

Page 23: ...ayed completely before the measurement occurs Different software and hardware versions use different strategies but all SRX_400 data collection programs employ automatic gain reduction noise blanking or delayed power measurements and time window discrimination in one form or another In the examples below we use two versions of the data acquisition program Event_Log which is designed to recognize t...

Page 24: ...4 19 20 23 16 16 21 22 24 23 18 18 28 30 20 14 16 24 22 19 16 28 23 16 20 13 19 19 28 18 28 22 34 21 34 24 38 24 38 26 42 21 16 25 42 27 44 29 20 27 44 28 46 35 23 28 46 29 47 39 25 29 47 29 48 42 27 29 48 30 49 44 28 30 49 30 49 46 29 30 49 30 50 47 29 30 50 30 50 48 30 30 50 30 Since the noise at both frequencies was bursty the gains in the first half of the trial can be seen to fluctuate while ...

Page 25: ...ideal conditions high signal to noise ratio but in the presence of noise the action of the local gain reduction algorithm would slow down acquisition so that this would not generally be possible In the first series of runs the gain was set at 60 substantial received noise the global noise threshold was disabled set to 50 and the noise blank level was adjusted to see whether the interfering signal ...

Page 26: ... beater is back Trying blank level 54 10 11 89 15 01 05 151 149 2R 169 151 158 3R 135 151 450 58 102 151 138 96 87 10 11 89 15 02 05 151 149 2R 173 151 450 64 95 151 138 96 98 10 11 89 15 03 03 151 149 2R 164 151 158 3R 132 151 450 64 66 10 11 89 15 04 25 151 450 64 89 151 138 96 84 151 149 2R 172 151 158 3R 80 10 11 89 15 05 04 151 450 64 88 151 138 96 92 151 149 2R 175 10 11 89 15 06 08 151 158 ...

Page 27: ...th 200 fish on 200 individual frequencies and with 6 local antennas located around the entrance to a fish ladder the time required to look for each animal once on each antenna is 1200 t n seconds where t is the transmitter pulse interval and n is the receiver processing time typically about 200 msec For pulsed carrier transmitters operating once per second this gives a round trip time of 24 minute...

Page 28: ...ure then from the configuration submenu 1 Baud Finally use the UPARROW and DOWNARROW keys to select the desired speed and the SHIFT key to enter verify your selection Now back up ESC to the main COMM menu and select 4 Autoanswer The modem s AA light if there is one should come on and stay on and the receiver will report autoanswer on if the operation is successful The receiver will now be in autom...

Page 29: ... Port Connector and Null Modem Cable Receiver Back Panel Terminal or Computer Connector DE 9P Serial Port DB 25P NAME PIN PIN NAME DCD 1 8 DCD RXD 2 2 TXD TXD 3 3 RXD DTR 4 20 DTR GND 5 7 GND DSR 6 6 DSR RTS 7 4 RTS CTS 8 5 CTS ...

Page 30: ...Rev B 30 APPENDIX B Antenna Switch Control Port Pins 1 8 ASP_8 current switch or 5V active high logic levels A7 A6 A5 A4 A0 A1 A2 A3 1 o o o o o o o o 8 9 o o o o o o o 15 Pins 9 15 are at logic ground ...

Page 31: ...E in some software versions step 12 Set Decode Threshold will be performed first followed by step 7 7 The message Initialize tables and storage will be displayed Answer yes 8 The message Program frequency range will be displayed Answer yes 9 When the Enter start frequency message is displayed enter the base frequency of your receiver in MHz The start frequency may be found on the label located on ...

Page 32: ...ould show up after hitting SHIFT F1 which initiates the New Prom procedure Confirm the first menu dialogue with Yes It is not necessary to further proceed with the initialization For a receiver equipped with dual bank version firmware W40 it is necessary to do the following Press SHIFT F3 normally used to toggle between the environments The message NewProm will be displayed the same message which ...

Page 33: ...ility is that the new PROM routine data has not been entered correctly There is also a small possibility that there is an electrical fault in the receiver The actual receiver frequency will differ from the selected frequency if the synthesizer count value is not correct 19 SRX_400A Eprom Replacement ...

Page 34: ...ee that interference will not occur in a particular installation If this equipment does cause harmful interference to radio or television reception which can be determined by turning the equipment off and on the user is encouraged to try to correct the interference by one or more of the following measures Reorient or relocate the receiving antenna Increase the separation between the equipment and ...

Page 35: ...uter remote control from 15 28 increment setting value of 9 intercharacter delay 15 Interval SIGNAL function 3 10 11 12 18 19 22 24 25 26 key functions in SCAN and SIGNAL routines 12 local maximum in SEARCH function 9 memory 3 5 6 7 9 12 13 15 20 extended 6 memory effects of batteries 5 Neighbourhood of SEARCH function 10 New_Prom routine 7 noise 3 10 11 13 16 18 19 22 23 24 25 26 noise blanking a...

Page 36: ...Rev B 36 terminal mode 15 28 time time and date function 14 typographic conventions 3 window for pulse interval 7 10 11 12 19 20 22 23 XON XOFF 15 ...

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