FR2458852A1 - Radio controlled transportable traffic signals - uses low power low frequency radio transmissions, digitally encoded, to control multiple transportable traffic lights - Google Patents

Abstract

The control of transportable self-powdered sets of traffic signals is by transmission of coded low frequency (1kHz to 3kHz) radio signals from a master station to one or more slave stations. To minimise battery drain, low powder radio transmission is used, digitally encoded to guard against interference with the low level signal and to allow one master station to control several slaves which respond only to preset codes. A keyboard is provided at the master station to set the control sequence. A microprocessor accepts data from the keyboard and displays the nominated traffic signal sequence in addition to performing the timing and encoding of signals to each slave station. A fail-safe facility is provided by setting the traffic signal to red when no signal passes the input filters of the slave receiver.

Description

The invention relates to a light, mobile, radio-controlled road signaling method, in the range of frequencies allocated to the industrial remote control, operating on 12 volt and 24 volt batteries.

 Known devices of this type remotely controlled by radio do not include a multiple coding process. The system presented has the particularity of sending information to the receiver by discontinuous radio link.

 Several low frequency modulations are transmitted in sequential cycle corresponding to the carrier transmission time which is established every 2, 3 or 4 seconds, and this during the duration of the receiver green light program.

The start of the sequence starts with the start of the program which cannot be less than 5 seconds and more than 3 minutes.

This process is the coding system.

 Decoding at the receiver is carried out in reverse, active filters select the frequencies received in order and this, during the programmed time, with a minimum and maximum constant level. If one of the pieces of information is not received or decoded, the receiving light remains in red, which avoids having the two lights blocked in green, and thus ensures an important safety of non triggering with various radio transmissions.

 Due to their mobility, the lights can be placed in places that are difficult to access, and at distances of up to 5 km from each other.

The radio link, despite its low power, is not affected, since the transmitting and receiving antennas are omnidirectional.

 The battery operation of the stations allows great ease of use.

Given the average consumption, less than 2 amperes, the invention allows great autonomy with the use of batteries of 190 amps / hour.

 The visualization by display of the programmed time allows rapid corrections in the event of crowding on a track.

Programming using the keypad, with visualization, ensures correct calculation of passage and jump-off times.

In the event of an error, a reset device cancels the previous programming.

The method according to the invention, for controlling the light signaling of two mobile stations, consists in programming on a keypad with keys, and in displaying the sequences of the green passage times, and of the red barrier.

 These functions are performed from a microprocessor.

The programming times, adjustable from 5 seconds to 3 minutes, can be programmed from 10 seconds to 10 seconds, for a total of 20 programs, valid for the two mobile stations.

 The remote control of the receiving station is carried out by radio link. The carrier transmits for the time necessary to send the low frequency modulation, between N and N frequency.

Keeping the preceptor station green will depend on the programming, and to do this, coded pulses will be sent every 2.3 or 4 seconds to the transmitter. The receiver will decode, according to the principle of active filters, the pulses received with the carrier. During the absence of transmissions or in the event of reception of bad coding, the receiver will remain blocked in red.

 The emission is of low power, it is carried out by means of an omnidirectional antenna.

 The programming carried out by means of the keypad located on the device, controls the microprocessor for the times displayed, and this according to a continuous sequential rhythm.

 The main station changes to green, stays according to the duration envisaged, then starts to red and this, during the programmed time.

At the end of the red cycle, the main station starts again for a new red cycle, but coded information is then transmitted to the receiver which, after decoding, turns green during the scheduled cycle; at the end of the receiver green cycle, a new red cycle is triggered, then at the end of this new cycle, the main station returns to green.

The coded emission is obtained from an electronic system controlled by a quartz, and which allows every 2, 3 or 4 seconds, to transmit the carrier for brief moments, and to send on this carrier, low frequency information , in a specific order at fixed frequencies.

 The receiver decodes the information received in order, and converts it into logical electrical signals, which make it possible to view the traffic lights.

 The emission is carried out in the band of 151.510 l ^ MHZ, this frequency remains single, even in the event of plurality of transmitters and receivers, only the codings in frequency modulation change.

 This is possible given the available frequency band, from 950 Hertz to 3,000 Hertz, and respecting a deviation of 100 Hertz per code, the process allows us 20 different codes, for the detection of the carrier, and 20 other codes different for modulation detection.

 Combinations in sub multiples of ten can also be adopted, which allows us to 20 x N codings.

 According to a second operating mode, it is possible to use, from a main transmitting station, several receiving stations up to the necessary limit; but the most often used case is the so-called 4-pass or 6-pass system, depending on this operating mode, there are several possibilities.

a) use the receivers in parallel,
b) perform an alternate sequence; 1st time, main light - 2nd time, 1st receiver - 3rd time, 2nd receiver - 4th time, 3rd receiver - 5th time, 4th 6th time receiver, 5th receiver - or perform a staggered function, this can be done from the microphone -processor central unit, and multiple coding; each receiver decoding according to the frequencies fixed in the decoding template which is an active filter.

Claims (6)

 1. A three-color traffic signal control method, characterized in that it consists of  a) be mobile and autonomous, by its operation on accumulator batteries, b) order sequences of green passage and red barrier, from a microprocessor,  c) carry out the programming of the sequences, using a keypad,  d) view the displayed programming, in real time,  e) send coded information from the main station discontinuously.  2. Method according to claim 1, characterized in that the transmitted radio wave comprises several low frequency pulses. 3. Method according to claim 2, characterized in that the receiver can decode the pulses transmitted by the main station, according to its frequency mask. 4. Method according to claim 2, characterized in that the transmitted pulses are carried out in a rigorous order and at fixed frequencies. 5. Method according to claim 1, characterized in that the main station can control several receiving stations by a common sequence, or by alternative sequences.  6. Method according to claim 2, characterized in that the receivers are provided with active filters specific to their decoding, and therefore can only decode what is allocated to them.