Identification, Interference and Tests

Two Articles of the Radio Regulations govern almost everything you will ever be pulled up for. Article 19 says that every transmission must be identifiable and that a call sign must be your own. Article 15 says that you must not get in anyone else’s way, must use no more power than the job needs, and must not clutter the band with signals that carry nothing. Between them they are the reason a monitoring station can find you, and the reason it usually does not need to. Both are examined directly, and both are quoted almost word for word in your Indian licence conditions.

Article 19 — identification of stations

The general obligation is the first line of the Article, and it is broader than most candidates expect:

Notice what 19.1 does not say. It does not say “amateur transmissions”, it does not say “below 30 MHz”, and it does not say “international contacts”. It applies to all transmissions, and the examiner builds distractors out of exactly those three false narrowings.

The Article then lists the services whose transmissions should carry identification signals, and the amateur service is the first one named, ahead of broadcasting, the fixed service below 28 000 kHz, the mobile service, and the standard frequency and time signal service. Radiobeacons and satellite EPIRBs are dealt with separately, and a short list of exemptions covers survival craft stations, radar transponders and the like.

No. 19.16 sets out the permitted forms of identification. A station may be identified by its call sign, by a maritime mobile service identity (MMSI), or by other recognised means — the name of the station, its location, the operating agency, an official registration mark, a flight identification number, or a selective call number or signal. For an amateur, only the first of those is ever in question: your identification is your call sign, unaltered.

What an amateur call sign may look like

No. 19.68 lays down the pattern. A call sign shall consist of either one character — and only if it is B, F, G, I, K, M, N, R or W — or two characters, followed by a single digit other than 0 or 1, followed by a group of not more than four characters, the last of which shall be a letter. No. 19.68A allows an administration to authorise longer call signs temporarily, for special occasions.

The call sign series allocated to India

Appendix 42 of the Radio Regulations divides the whole alphabet-and-digit space of prefixes among the member states. India holds exactly three blocks:

Shortened to the form the licence paperwork uses, India’s series are 8T–8Y, AT–AW, VT–VW and VU. The point of exam detail is that there is no separate VUA–VUZ entry in Appendix 42. VU is not an ITU allocation in its own right; it is simply the part of the VTA–VWZ block that India has chosen to use for amateurs. A question offering “VUA to VUZ only” is offering you a plausible-sounding wrong answer.

Call signs in India are allotted by the Wireless Planning and Coordination (WPC) Wing of the Ministry of Communications. You may state three preferences when you apply; the grant is subject to availability.

Prefixes you will hear from India, and the ones next to yours

The lesson to draw from the last three rows is that the characters before the digit are what identify the country, and that neighbouring blocks belong to countries thousands of kilometres apart. The call sign guide on this site lets you look up any prefix you hear.

Indian conventions on top of the ITU pattern

Within the space the ITU leaves free, India has made its own arrangements, and these are examined as Indian facts rather than ITU ones:

• VU2 — General grade. VU3 — Restricted grade. The digit tells a listener your licence class before you say a word.
• VU4 — Andaman and Nicobar Islands. VU7 — Lakshadweep and Minicoy. These are places, not grades; a VU4 call sign says nothing about the operator’s licence class.
• From 25 June 2025 new call signs are issued from the series VU21–VU29 for General grade and VU31–VU39 for Restricted, each followed by a two-letter suffix — VU32VV, for instance. Existing call signs are unchanged, so both forms are on the air together and both are correct.

Suffixes for temporary operation are national practice too. /P marks portable operation, /M mobile, /MM maritime mobile and /AM aeronautical mobile. The ITU does not prescribe any of these; what it does is permit an administration to authorise a temporary extension of the call sign (No. 19.68A). Whatever the suffix, the core call sign remains the one allotted to you, and you may not alter it.

How often you must identify

RR No. 25.9 requires amateur stations to transmit their call sign at short intervals during the course of their transmissions. The treaty puts no number on it, so the number is national. The Indian licence conditions do: identify at the beginning and end of each transmission period, and again whenever the period exceeds ten minutes. No transmission may be made without identification at all, and that includes tests. The licence conditions lesson covers the calling and answering procedure that this sits inside.

Article 15 — interference

Article 15 opens with a definition that must be reproduced exactly, because it is the definition the whole regulatory system turns on and because the exam sets three near-misses against it.

Three limbs, then. It is harmful if it endangers radionavigation or another safety service; or if it seriously degrades, obstructs or repeatedly interrupts a service that is itself operating lawfully. Two things are not in the test, and both are offered as answers: whether you can hear it, and whether it was deliberate. A signal you can merely hear in the background is interference — defined separately at No. 1.166 as unwanted energy causing degradation, misinterpretation or loss of information — but it is not harmful interference. The Regulations also recognise permissible interference, which complies with the quantitative criteria in the Regulations, and accepted interference, which is above that level but has been agreed between administrations.

The obligations that follow

Read No. 15.1 carefully before you answer a question on it. A CQ call is a purposeful transmission with a clear object, and is not a superfluous signal; nor is working a station in another Region, nor operating on a secondary allocation. What the provision catches is the carrier left keyed while you go and make tea, the long unidentified whistle, the deliberately false call sign.

No. 15.2 is a standing duty, not something you do when someone asks. The rule is the minimum power necessary for the contact you are actually making — which on 2 m across a city is very often the low-power setting on the handheld, not the high one. Turning the power down costs you nothing you can hear and removes you as a source of interference from an entire suburb.

The same rules in your Indian licence

The Indian licence conditions restate Article 15 in operational language, and the phrasing is worth recognising because papers quote it directly:

• The station must be so designed, constructed, erected, maintained and worked as not to cause interference with any wireless telegraph service functioning within or outside India in accordance with the Regulations.
• If interference is caused, the licensee shall discontinue or restrict transmissions pending adjustment of the equipment, on request.
• Emissions must be free from harmonics, key clicks, hum and spurious emissions; the transmitter must not be over-modulated; and class B damped wave emissions are forbidden.
• Only the minimum power needed to make the contact may be used.
• Before transmitting, ensure your signals will not interfere with transmissions already in progress; if they would, begin only at an appropriate break. On CW that is QRL?; on phone, “is this frequency in use?”
• A reliable frequency measuring device must be available at the station, and the frequency checked each time it is changed, so that nothing is radiated outside the authorised bands.

The licence conditions lesson lists these in full alongside the rest of Annexure I.

Tests and adjustments

Section IV of Article 15 deals with tests, and it is the part of the Article that applies to an amateur most often.

No. 15.14 requires an administration, before authorising tests and experiments, to prescribe all possible precautions to avoid harmful interference — naming three in particular: the choice of frequency, the choice of time, and the reduction or, if possible, the suppression of radiation. No. 15.15 requires any harmful interference resulting from a test to be eliminated as soon as possible, and confirms that the identification requirements of Article 19 apply to test transmissions as much as to any other. No. 15.17 adds that signals for testing and adjustment must be chosen so that no confusion can arise with a signal having a defined meaning in the Regulations.

India puts numbers on all three ideas:

The dummy load is the piece of equipment that turns most of this from a rule into a habit. A 50-ohm resistor of adequate rating, connected in place of the antenna, lets you tune, measure power and check modulation while radiating almost nothing. It costs a few hundred rupees and it is the difference between an experimenter and a nuisance. The bench tools page has the rest of the test kit.