Verantwoordelijke uitgever: Ph. THYSEBAERT : éditeur responsable. Av. de l'europe 4, 1330 RIXENSART. - PDF

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R.O.C. NEWS driemaandelijks tijdschrift bulletin trimestriel 15e année N 58 août 1984 jaargang augustus Verantwoordelijke uitgever: Ph. THYSEBAERT : éditeur responsable. Av. de l'europe 4, 1330 RIXENSART.

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R.O.C. NEWS driemaandelijks tijdschrift bulletin trimestriel 15e année N 58 août 1984 jaargang augustus Verantwoordelijke uitgever: Ph. THYSEBAERT : éditeur responsable. Av. de l'europe 4, 1330 RIXENSART. INHOUDSTAFEL; -R/O TOESTAND. 16/7/84. -THE RADIO LIGHTHOUSE. -BREUGHELS FESTIJN - ROC. vrijdag 7/9/84. - Qrx in het club house,j.jordaensstraat 26, 1050 te Brussel,elke eerste vrijdag van de maand vanaf uur. - De ledenbijdrage is vastgesteld op 350 fr,c/0 Radio-officers club, Nr te Brussel - Redaktie ROC-News : Roger Retelers,Kasteelplein 24 te 2300 Turnhout, tel 014/ SOMMAIRE : -SITUATION O/R 16/7/84. -THE RADIO LIGHTHOUSE. -BUFFET CAMPAGNARD DU ROC, vendredi 7/9/84. -QRX Club House rue Jacques Jordaens 26, 1050 Bruxelles, chaque premier vendredi du mois à partir de 20h00. -La cotisation est fixée à 350 F.,c/o Radio Officers Club, c/c à Bruxelles. -Rédaction ROC NEWS :Roger Ketelers,Kasteelplein 24, 2300 Turnhout.Tel.0l4/4l3340. SITUATION TOESTAND - R / 0-16/7/1984. BLOYAERT J. BOLLE D. BOUGARD M. CARMOT P. COLLARD D. COOLES C. CROISSIAUX CUVELIER J.CL. DEBONTRIDDER G. DEJARDIN H. DELMOTTE G. DEMAEYER L. DEMEERSMAN JP. DEHOUSTIER M. DE NEEF G. DREESEN L. DOBBELAERE D. FOURET JP GEURTS G. GOOR RINGELET GOUSSAERT G. GRAEVENITZ N. GUNAWARDENA N. IMPENS D. JACOBY A. JACQUET F. JADIN P. LABAT D. LIMPENS M. MOSIN R. MOTTE R. FED. SKEENA ANTWERPEN CORN. VEROLME ORINOCCO FED. HUNTER RUTH BRDSSEL PERMEKE METHANIA MIN. LUXEMBOURG AMAZON MAASKANT ELLEN HUDIG EEKLO ORTELIUS KIJOTO FINA AMERICA MERCATOR DELORIS FED. OTTAWA MAASKERK QUELLIN YAFFA FED. MAAS ENSOR MIN. SAMITRI HELEN FED. DANUBE MAGRITTE ZEEBRUGGE MIN. GENT NEUFCOUR M. NAVEZ FR. OOSTEROM C. PARREN CH. PATERNOTTE J. PETIT E. PIRLET J.P. PLAISANT RENARD A. REYNDERS G. THEYS TROUBLEIN I. TUBBAX L. VANDERSTRAETEN K. VAN ESPEN E VAN ROGGEN E. VAN SANDE R. VAN SCHOENBEEK E. VAN MALLEN 0. VERVUST T. WAERZEGGERS K. WARGNY M. TEMSE MIN. HOBOKEN MIN. ALGERIA FABIOLA VILLE MIN. MARCHIENNE VESALIUS PLANTIN FED. HURON MAASTKROON FED. THAMES MARTHA L P C PETREL VANDIJK MAASKADE TIELRODE MIN. ANTWERPEN DART CONTIENT LUMUMBA CMB EUROPE FINA BELGICA FED. HUDSON The Radio Lighthouse Summary The Radio Lighthouse is a radio navigation aid designed specifically for smaller coasters, in-shore fishing boats and pleasure craft. Additionally, it has shown itself to be a very useful aid for larger vessels when their other navigation receivers suffer breakdown caused, for instance, by heavy electrostatics. It provides bearing information for any ship within the coverage area equipped with a suitable VHF communications transceiver or receiver. No other on-board equipment is required. Furthermore, the radio Information received is independent of the ship's heading and, therefore, its roll, pitch and yaw in heavy seas. This makes the task of obtaining the bearing very easy. Unlike conventional Non- Directional Beacons, no calibration curves are required. The equipment has been developed at Standard Telecommunication Laboratories (STL) in Harlow, Essex. Description of Operation The Radio Lighthouse operates in the International Marine VHF band at approximately 160 MHz. When tuned to the correct channel an audio tone will be heard. The transmitter is so arranged that the tone may be heard in all directions from the transmitter, except one radial along which there is a marked reduction in tone level. This radial, sometimes referred to as the 'Null Radial' is slowly rotated by the transmitter at a rate of 4 degrees per second. Knowing this rate and the reference time at which the radial passes through a 'Reference Bearing' which is published for each beacon, it is possible to obtain one's bearing by noting the duration from the reference time until the quiet radial passes through the bearing at which the receiver is located. To make this time estimation even simpler, the transmission is broken into a series of beats 0.5 seconds long. Now the bearing may be obtained by counting beats from the reference time until the Null Radial passes through the receiver. While the radial is approaching, the tone is gradually decreasing in intensity and after the radial has passed through the receiver, the tone gradually increases again. This rotation by the 'Null Radial' is carried out electronically while the antenna is physically fixed. Thus, there are no mechanically moving parts at the transmitters. Signal Format for each Beacon Transmissions commence on the hour and every minute thereafter. Each transmission lasts 58 seconds, there is then a pause before the next one commences. The 58 seconds are composed of several parts, as follows: (a) Morse Identification This tells the navigator which is the transmitting beacon. (b) Navigation This is the part of the transmission which enables the navigator to determine his bearing with respect to the transmitter. (c) Morse Identification This repeats (a) above. There are some pauses in between the various parts to make it easy for the navigator. Between (a) and (b), as well as after (c), there is transmitted some digital data which is used by test instruments. The Navigation part comprises 70 beats each made up of 0.4 second of tone and 0.1 second of quiet. Of these, beats 7 to 67 (both inclusive) are used for navigation purposes. During these beats, the 'Null Radial' sweeps a 120 degrees azimuth sector which is the beacon's published coverage sector. As seen on a chart the radial sweeps clockwise from the bearing corresponding to beat 7 to the bearing corresponding to beat 67. Beats 1, 2, i and 4 are there to help the navigator get the counting rhythm, beat 70 marks the end of the sequence. Figure 1 shows how the tone intensity varies at different bearings from the transmitter. The further into the 1 20 degrees sector the navigator is. the higher the beat number he get* to before the 'Null Radial' is observed to pass. If the null is heard during beats 3, 4, 5, 6, 68 or 69, then the navigator should conclude he is outside the published sector. Time Sharing of Several Beacons In order to conserve frequency spectrum, it is possible to arrange several beacons to time share a common frequency channel. There may be two such beacons alternating with 58 seconds each and 2 seconds inbetween when neither transmit, or there (nay be three or six beacons taking turn about. In all cases, the navigator can determine which beacon is transmitting by listening to the morse identity before and after the navigation part. Methods of Use The navigator may use the Radio Lighthouse in four different ways: (a) Radials drawn on chart If a beacon is used regularly, it may be worthwhile drawing on the chart the 120 degrees information sector for the beacon. The extremities of the sector are marked beats 7 and 67 respectively and a convenient number of radials at equal spacing may be drawn in between. In Figure 2 a navigator has drawn in the radial for every fifth beat corresponding to every 10 degrees as it applies to the North Foreland transmitter from early To use the system, listen to the transmissions, wait for the correct morse identity, count beats until the 'Null Radial' is heard (i.e. minimum tone level) and read the corresponding radial on the chart. (b) Plastic overlay Associated with this description is a clear chart overlay marked with some of the bearing lines. On these bearing lines are shown the beat number during which the tone level reaches its minimum lor that bearing. Position this overlay on the chart in use, such that the point on the sheet marked Transmitter coincides with the known position of the transmitter on the chart. Align the 120 degrees azimuth sector such that the line marked 7 points in the direction corresponding to the station's 'Reference Bearing'. Now listen for the correct morse identification and then count the navigation beats until you hear the minimum. The bearing is now found by referring to the chart overlay. (c) Formula based on counting It the overlay gets lost, navigation may be conveniently effected by applying the beat with minimum tone to the simple arithmetic formula: B - R + 2 (N - 7) where B is the true bearing from the transmitter towards the ship, N is the beat number with minimum tone, and R is the 'Reference Bearing'. This formula, as well as the published reference bearing for all beacons of interest, could be written in the chart margin or fixed to the VHF receiver. (d) Formula and time measurement. For those who dislike counting, the alternative is to use a stopwatch. Start it during beat 7 and stop it during the beat with minimum. If T seconds elapsed, then the bearing from transmitter to the ship is given by: B = R + 4T where R is the 'Reference Bearing' as before. This is found particularly useful when taking bearings which involve counting a large number of beats. The above four methods show there are a variety of ways in which the system may be used. Navigators develop their own technique to suit their own inclination. Whichever method is employed, the overall rule is; first check that (he morse identity is what you expect. then find the beat with minimum tone intensity and finally check the morse identity again. Counting to 70 may seem tedious, particularly when tired or seasick. To ease the task, a marker is transmitted every 10th beat. Thus, the 10th 20th up to and including the both heat, are transmitted at a slightly lower audio frequency. above water level and clear of other structures and using a good quality coaxial cable, then a 20 nautical mile range can be expected from a transmitter with antenna at 57 metres above sea level, where the transmitter feeder losses are less than 2 db. Halving the transmit antenna elevation will reduce the range to approximately 70%. Suitable Radio Receivers The system is designed for use with the standard marine transceivers already installed on most ships. Whether it is a svnthesised set or a crystal controlled one does not matter as long as it is fitted for the frequency in use. Thus, it is possible to do the navigation using the communications receiver with no extra equipment on board. Mounting the Transmitter The system is designed to be operated at unmanned coastal sites. All that is required is a power supply, a room in which the equipment bay may be protected and kept safe and a suitable antenna mounting place. The antenna is lightweight since it is constructed mainly from aluminium and it may be mounted on a lighthouse or coastguard building wall or on a tower or similar structure. The antenna comprises corner rejectors each made of simple reflector rods. The system therefore presents minimum area to wind. Range The system range depends on the following factors: (a) (b) (c) Transmitter antenna elevation; Receiver antenna elevation; Type and mounting of the receiver antenna; (d) Cable losses at transmitter and receiver; (e) Receiver type. If the receiver is one built to the standards envisaged by Appendix 14 of the Radio Regulations and it it is connected to a dipole mounted 28 feet Information Sector This is 120 degrees end to end. If 240 degrees is required, then two transmitters may be used each covering its own 120 degrees sector. System Accuracy During 1981 over 1000 measurements of system accuracy were carried out. These indicate a standard deviation of about 2 degrees or about ±4 degrees for 95% of cases. Thus, while moving through the sector from one end to the other, there is a 1 in 20 chance that the error in using the system will exceed + 4 degrees. System Stability During 1982 far field monitors were installed in three fixed locations so that the long-term stability of the transmissions could be assessed. In the half year period March 1981 to September 1981, over 800 readings were taken. These show a spread with standard deviation better than 0.5 degree. Steps taken to Safeguard the Navigator It is clearly important that the navigator shall have confidence in the integrity of the system. To this end, (here is in each transmitter a built-in monitor which automatically and continuously checks the system perlormance. If a fault develops (permanent or transitory) then the system will immediately signal this to the navigator by warbling the audio tone (varying it between two distinct frequencies). If this happens, the navigator should not use the bearing information transmitted. -Bericht aan de lekkerbekken - Getrouw aan de traditie om buiten het jaarlijks banket van de ROC nog een smukpartijtje te organiseren in ons Club huis : hieronder alles over een gastronomisch gebeuren op 7 September. Om de organisators het werk te verlichten verwacht men de inschrijvingen op ten laatsts 15 Augustus. BREUGHELS FESTIJN VRIJDAG 7 SEPTEMBER OM UUR IN HET ROC -CLUB HOUSE. LANDELIJKE KLEDIJ IS WENSELIJK Inschrijving via storting van slechts 250 fr per persoon op Nr van de ROC met de vermelding Breughel Festijn * Avis aux gourmets(et gourmands).fidèle à la tradition,avant le banquet extra muros,voici 1'annonce de la soirée gastro du club.pour faciliter l'organisation prière de s'inscrire avant le 15 aout. Merci. BUFFET CAMPAGNARD : Vendredi 7 septembre 1984 a 20h00. au CLUB HOUSE ROC,rue J.Jordaens. Tenue de Campagnard souhaitée. Inscriptions via versement de 250 F. par personne au cc du ROC avec mention Buffet campagnard .
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