NFA-L25RSAnti-Two-Block Transmitter

L25 Radio A2B LIFT ek Corporation page 1 Operator / Maint. Manual Copyright © 2000 All rights reserved. LIFTek™ Corporation L25 SERIES RADIO ANTI-TWO-BLOCK SYSTEM OPERATOR and MAINTENANCE MANUAL Manual P/N L2560 rev - August 2000 This device has been tested and found to comply with the limits for a Class A digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment. This equipment generates, uses and radiates radio frequency energy, and if not installed and used in accordance with this instruction manual, may cause harmful interference to radio communications. Operation of this equipment in a residential area is likely to cause harmful interference, in which case the user will be required to correct the interference at his own expense. RAT SWITCH (transmitter) MODEL-S/N L25RS - ______ RADIO A2B DISPLAY (receiver) MODEL-S/N L20D - ______ for PARTS, SALES AND SERVICE CONTACT YOUR DEALER file: MBTmanual1.doc L25 Radio A2B LIFT ek Corporation page 2 Operator / Maint. Manual Copyright © 2000 All rights reserved. WARNING! READ THESE INSTRUCTIONS Read and follow all safety rules and instructions before operating this equipme nt. Improper operation can lead to system failure, property damage, personal injury or loss of life! Customer responsibilities The manufacturer has taken every precaution to make this a reliable system. However, it is the operator’s responsibility to follow the instructions in this manual, and to use the system properly. Training 1. Read this manual carefully. Learn how to operate the system and how to perform daily inspections and test procedures. 2. Never allow anyone who has not been properly trained to operate the system. 3. Use the system only as intended and as described in this manual. 4. Keep the manual, refer to it as needed, and review it often. 5. If you don’t understand something - call the factory or distributor. There is no charge for this assistance. Inspection and Test 6. Follow the daily inspection and test procedures. 7. Failure to inspect and test the system can lead to system failure - see warnings. 8. Test the hor n for loud ness - empty any water that collects in the front cavity (especially if mo unted o utside). Water can reduce sound output Operation 9. Understand how the system works and prevent and/or correct any conditions that might degrade the system performance. 10. Do not operate a damaged system. 11. Inspect and test the system thoroughly if you suspect physical damage of any kind has occurred, including: contact with structures, tree branches, or an excessive pull on the line w eight. 12. Maintain a clear line of sight between the boom tip transmitter and the display panel receiver. Metal barriers in the path can block the signal and prevent the system from working. 13. Do not rely on this system if excessive radio interference is present. This may occur near radio/TV towers. If in doubt, perform a System Test. 14. Do not shorten the chain. Do no t alter the sys te m i n a ny way witho ut writte n approval fro m the manufacturer. 15. Do not use the switch override clip if the flag is missing. 16. You should monitor all active winch lines with an operating two-block switch. 17. Always keep the weight securely fastened around the crane cable or stowed in the cab. NEVER allow the weight to swing freely from the switch. A free swinging weight is a ha zard. 18. Never stand under any suspended object. 19. Never use the system as a control device to routinely stop the hoo k w hile w inching up. WARNING! This is an operator’s aid. Never rely solely on any system to prevent two-blocking. Part failure, excessive radio noise, or damage can prevent two-block detection. No system is 100% failsafe. Two-blocking can cause property damage, personal injury or loss of life! Check the system for proper operation as recommended in this manual to reduce the chances of a malfunction during crane operation. L25 Radio A2B LIFT ek Corporation page 3 Operator / Maint. Manual Copyright © 2000 All rights reserved. TABLE OF CONTENTS L25 Operator and Maintenance Manual Warnings and Customer Responsibilities............................................................................ 2 L25 Introduction.................................................................................................................. 4 Quick Reference For Operators .......................................................................................... 4 RAT SWITCH Operation.................................................................................................... 5 How to rig, inspect, test and override. Display Panel Operation KEYS:...................................................................................................................... 6 BYPASS...................................................................................................... 6 HORN OFF ................................................................................................. 6 TEST (display only) .................................................................................... 6 LEARN/ UNLEARN RAT SWITCH ........................................................ 7 LIGHTS AND ALARMS:...................................................................................... 8 TWO BLOCK alarm ................................................................................... 8 RECEIVING: Switch 1, 2 ........................................................................... 8 RECEIVING: Low Battery alarm ............................................................... 8 NOT! RECEIVING alarm........................................................................... 8 Operator’s Daily Inspection and System Test ................................................................... 10 Maintenance Procedures ..........................................................…

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LIFTek C O R P O R A T I O N 610 North Main S t. Memorial Bldg. Suite 295 Blacksburg VA 24060 - 3349 Toll Free 1-888-LIFTek8 Phone 1-540-951-2595 Fax 1-540-951-9384 Summary of operation for NFA-L25RS transmitter (418 MHz) This device is a wireless limit switch used on mobile cranes. This type of safety system – called an anti-two block system – is required by law on nearly all cranes built in the U.S. to prevent damage to equipment, injury and loss of life. Most of the time the limit switch is in a no n-alarm state and sends only a periodic update signal (3 packet burst) every 11-16 seco nds to report its status (15.231(e)). The aperiodic alarm signals are sent as described below and in accordance with 15.231 (a) (1,2,4) and (b). Periodic Operation Data format for this device is a pulse position scheme that consists of 16 data bits (.488 msec each max) and two start bits (first is .976 msec and seco nd is .488 msec). T he worst case ON time for one packet is 9.272 msec. The packet is transmitted 3 times in a row, asymmetrical spaced. This packet burst ( 347.456 msec total length) is repeated every 11 to 16 seconds. This yields a duty cycle of 20 log (9.272/100) = -20.66dB in a sliding 100 msec window. Average power is limited to 4133 uV/m during periodic operation (15.231(e)) by use of a T-pad attenuater and the transmit power co ntrol pin #4 on the transmitter IC. Aperiodic Operation The data is sent in the same format as above, except that when the limit switch is tripped by a crane operators unsafe action, the transmitter sends a packet every 125 msec (8 per second) for 5 seconds and then at a rate of 4 per second until 30 seconds has passed (15.231(a)(4)). Then the transmitter sends only at the periodic update rate described above. This signal stops the unsafe operation of the machine. When the operator clears the unsafe condition the alarm clear signal is sent for 5 seconds at 8 per second (15.231(a)(1,2)). This signal must be sent quickly to insure operation is returned to the operator as soon as possible. Aperiodic signals are sent at a higher power level which is allowed under 15.231(b). The higher power level is achieved using the transmitter po wer co ntrol pin #4. Under periodic operation the pin sees R17-430 o hms to gro und which limits power out to the periodic level requirements. During aperiodic operation the pin is shorted to ground (by the microcontroller) which increases power o utput by 6 dB - even though an increase of 8 dB is permitted by the rules cited above.

CD&T FCC ID: NFA-L25RS A. DEVICE UNDER TEST The product is remote control transmitter used as a safety alarm on cranes to indicate a hazardous condition. This device works in conjunction with a receiver (NFA-L20D) that was previously certified. This product is designed to operate in two states under the provisions of Part 15.231, both (a) and (e), of the FCC rules. The rational is explained in the Operational Description that accompanies this application. The transmit frequency is 418.000 MHz. nominal. The modulation mode is on/off keying using a pulse position scheme. This device only transmits command codes and is not used for data transmission. Power for the device is provided by an internal “C” size 3.6 volt lithium battery. The rf section consists of a Linx Technologies TXM-418-LC transmitter module, a four element antenna matching network and a detachable steel spring antenna. The antenna is custom manufactured by the applicant and is connected by a unique three part assembly that is not compatible with any standard electrical connector. B. MEASUREMENT PROCEDURE: RADIATED EMISSIONS Testing of this device was conducted at the Hyak Laboratory test facility located in Spotsylvania, Virginia. Transmitter field strength measurements were conducted according to the procedures set forth in ANSI C63.4 (1992). Testing was conducted with a fresh battery and monitored periodically to insure that the battery voltage (under load) was maintained at 95% of nominal or better. The device under test was placed on a rotating turntable 0.8 meters high, centered at 3 meters distant from the measurement antenna. The device was placed in the center of the turntable and tested in two positions shown in the test setup photographs. For the purpose of testing, the micro-controller in the test sample was set to transmit a constant 1 kHz. pulse stream continuously. The field strength measurements were taken using a Tektronix 494P spectrum analyzer, EMCO 3121C dipole set, an EMCO 3115 double ridge guide horn and an Avantek UJ210 preamp. The device was scanned from 30 MHz. to 5 GHz. and all emissions were noted. In this case, the only emissions detected were those harmonically related to the fundamental transmit frequency. Two sets of radiated emissions measurements were taken for this device. One set for the 15.231(e), low power state and one for the 15.231(b), high power state. For both tests, at each frequency of emission, the device was measured by rotating the turntable and adjusting the antenna height over a range of 1 to 4 meters to obtain the maximum output level. This procedure was performed with both horizontal and vertical antenna polarizations for both of the setup positions shown in the test setup photos. The peak reading for each frequency was recorded in the second column on the data sheets. Measurements taken for weak emissions were performed by reducing the distance from the measurement antenna to 1 meter and factoring –9.54dB into the calculation. For the low power state this procedure was used for the 5 th and 6 th harmonics. For the high power state this done for the 6 th , 7 th and 8 th harmonics. C. DUTY CYCLE AND PERIODIC INTERVAL CALCULATIONS The occupied bandwidth and duty cycle measurements were made using an HP8596E spectrum analyzer and plotted with an HP7475A pen plotter. While the computations below were drawn from the timing diagram, the plots verify the computations and indicate that the duty cycle taken from the sample is slightly less than one derived from the timing diagram. The code format for this device is a three packet burst, pulse position scheme that comprises 16 data bit frames and 1 start bit frame for each packet The packets are asymmetrically spaced with a period of 347.456ms. from the rising edge of the first packet pulse to the falling edge of the last pulse of the third packet. The frame windows are divided into 4 sectors of 0.488ms. each, giving a frame window of 1.952ms. This gives a total packet length of 33.184ms. Except for the start frame, the on time of any data bit is equal to 25% of the frame window or 0.488ms. The start frame has an on time equal to 75% of the frame or 1.464ms. Referring to the timing diagram: 1) the start frame is high in the 1 st , 2 nd and 4 th frame sectors 2) a logic “one” is high in the 1 st sector and, 3) a logic “zero” is high in the 3 rd sector This gives a total on time of: 1 start frame (1.464ms.) + 16 bit frames (16 X 0.488ms. = 7.808ms.) = 9.272ms. The time from the start frame of the first packet to the start frame of the second packet is 197.152ms. The time from the start frame of the second packet to the start frame of the third packet is 117.120ms. This spacing insures that not more than one packet is issued in any 100ms. time frame. The duty cycle correction factor derived from this is: 20log (9.272ms./100ms.) = - 20.66dB As provided in Part 15.35 of the FCC rules, a correction factor of –20dB is used for the calculations on the data sheets. The provisions of 15.231(e) require the silent period for this device to be 10.424 sec. (30 X 347.456ms. = 10.42368 sec.) As shown in time domain plot 6, the repeat rate from this sample was 13.650 seconds giving a silent period of 13.303 seconds. (13.650 – 0.347456 = 13.302544). The repeat rate varies between 11 and 16 seconds and is independent of the frame and packet timing. This is done for collision avoidance where multiple systems are used in close proximity. TIMING DIAGRAM msecmsecmsecmsecmsecmsec 43214321432143214321 1.9521.9521.952 START FRAME BIT FRAMEBIT FRAMEBIT FRAMES 4 - 15 BIT FRAME 1216 1.9521.952 0.488msec BIT FRAME 3 "ONE""ZERO""ONE""ZERO" 1 START FRAME + 16 BIT FRAMES X 1.954msec = 33.184msec PACKET LENGTH PULSE WIDTH 23.424