1. Introduction

Most Shortwave Listeners may have noted those endless Morse Broadcasts: vvv de 4XZ 4XZ = =. From time to time messages in several formats are transmitted, which never are confirmed - at least not in a decodable mode.

4XZ is - officially - operated by IDF (Israeli Defense Forces) Navy in Haifa. This may be questioned however, as many properties of the network are those of a Number Station. 1999 Ary Boender's Numbers & Oddities presented a detailed description of 4XZ in Newsletter 14. Number station group ENIGMA 2000 called it M22 and published in January 2003 a station's profile, but later on cancelled M22 as a Number Station.

Major changes of the station in 2005 made me write this updated profile. I used my own database of the last years and received valuable - because old - logs of Ary Boender.

2. Transmitter site, frequencies and traffic load

Direction findings made by WUN members and myself during many years suggest the transmitters are in Israel. Other sites are not known. Because I didn't find high resolution satellite pics I only can guess about some transmitter sites. Those on Mt. Carmel are the closest to Haifa.
Operational standards are of a high standard. When long messages upset the timetable, transmission speed is increased. Weather bulletins were sent faster than other messages.

For many years and until July 2005 4XZ operated two independent broadcasts. Between 2001 and 2005 the sked was:

Broadcast 1: 2800//4241//5159//8103//10046//12984 kHz
Broadcast 2: 2680//4331//6379 kHz

Besides these standard frequencies others were used for days or even months at certain times. In July 2005, after a test period, BC 1 definitvely was switched off, BC 2 stayed on the air, but sometimes one of the frequencies is switched off or altered slightly for a short time.

The monthly traffic load is quite stable and evenly spaced:
Broadcast 1: was about 40 messages/day, about 1200/month
Broadcast 2: about 18 messages/day, about 550/month

The (real?) IDF Navy can be heard in a proprietary PSK Hybrid mode for example on:
7160//8780, 6775.3, 7866.3, 9253.3, 11461.3 and 13485.3 kHz

3. Message Formats

All broadcasts use the same transmission formats:

- idling with call-up
- messages in several formats
- traffic lists
- operational messages
- interrupt messages.

Format	Text	Remarks
Idling	vvv de 4XZ 4XZ = =	Repeated
Message announcement	nw QTC 1 nr 2701	New message number 1072 follows.
Repeat announcement	nw rpt nr 2701	Repeat of message number 1072 follows. Messages are at least repeated twice.
Traffic in encrypted 5-letter-groups.	= = nr 2701 xi v DN8I 009092 ED4K gr 73 = = (txt) = = nr 2701 xi v DN8I 009092 ED4K gr 73 = = (txt) = = nr 2701 xi v DN8I 009092 ED4K gr 73 = = + +	Message 1072 with repeat and ending. After 40 groups: "= = aa gr 04 = =", after 80 groups: " = = aa gr 08 = =", etc. Text is 5-letter-groups.
Traffic in Hebrew Morse code.	= = nr 7701 qc a COLC 439092 FW8I wnc = = (txt) = = nr 7701 qc a COLC 439092 FW8I wnc = = (txt) = = nr 7701 qc a COLC 439092 FW8I wnc = = + +	Message 1077 with repeat and ending, text is figure-letter-groups with punctuation. Not heard since January 2006.
Surface analysis/forecast in WMO FM46-IV	= = nr 6701 qc z WT6D 038092 KS5X wnc = = (txt) = = nr 6701 qc z WT6D 038092 KS5X wnc = = (txt) = = nr 6701 qc z WT6D 038092 KS5X wnc = = + +	Message 1076 with repeat and ending, text is 5-figure-groups. Not heard since January 2006.
Traffic list.	nr 394 fo gr 73 = = QS1Z nr 694 so gr 61 = = QS1Z nr 594 lz gr 02 = = AD3Onr 494 je gr 31 = = AD3O nr 394 fo gr 73 = = QS1Z nr 294 ue gr 22 = = UO9D nr 694 so gr 61 = = QS1Z nr 594 lz gr 02 = = AD3O nr 494 je gr 31 = = AD3O nr 194 bo gr 02 = = KL1Z nr 984 so gr 52 = = QS1Z nr 394 fo gr 73 = = QS1Z nr 294 ue gr 22 = = UO9D nr 694 so gr 61 = = QS1Z nr 594 lz gr 02 = = AD3O	The list shows the complex transmission sequence of messages and repeats.
Operational message.	RE4P RE4P QSL nr 261	RE4P should confirm message 162.
Operational message.	OW7E OW7E OW7E nr 5011 to 8011 4111 to 7111 QQL = =	QQL unknown, maybe OW7E should delete messages 1105 to 1108 and 1114 to 1117.
Interrupt message.	sri sri sri vvv de 4XZ 4XZ = = + + nw QTC 1 nr 896	Any traffic is interrupted and a new message follows. This may be due to an op error or because the new message has priority.

4. Message preambles

= = nr 2701 xi v DN8I 009092 ED4K gr 73 = = ekeke wmhit ....

Text	Remarks
nr 2701	Message number 1072 in reverse order. Reset the last day of the month.
xi	Purpose unknown.
v	Message identifier. a = Hebrew Morse, v = encrypted 5-letter-groups, z = weather bulletin.
DN8I	Addressee.
009092	Day and local message preparation time: 29. at 0900 in reverse order.
ED4K	Sender
73	Group count 37 in reverse order. In Hebrew Morse and weather messages replaced by "wnc".
ekeke	Normally first and last letter of sender, may be an additional check. In weather bulletins replaced by "onden".
wmhit	Second group, same as the last group.

5. Downloads

All logged frequencies between 1987 and April 2006.
Samples of messages in all 3 formats.
Traffic statistics between January and September 2004.

6. Latest News

January 2006:
Weather Bulletins and Morse messages in Hebrew Morse Code are not disseminated any longer.

Spring 2011:
The MOSSAD Number Station E10, after dekades of uninterrupted operation, ceased to exist. There was no impact on 4XZ operation.

Summer 2011:
4XZ with business as usual.

January 2012:
Additional frequencies came in use, but this time they did not vanish after a few days. 2680 kHz
4331, 4595 kHz
6379, 6607 kHz

April 2012:
Again more frequencies are heard in parallel on several or all of the following frequencies:
2680, 2833 kHz
4331, 4539, 4595 kHz
6379, 6525, 6607 kHz

December 2012:
These following frequencies are regularly on the air:
2680, 2860 kHz
4331, 4595 kHz
6379, 6607 kHz
5000 kHz was temporarely used around December 8th

Let's see what happens next!

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