FS-1045A: General Requirements

4 GENERAL REQUIREMENTS. The functional capability described herein includes automatic signaling, selective calling, automatic answering, and radio frequency scanning with link quality analysis (LQA). The capability for manual operation of the radio in order to conduct communications with existing, older generation, nonautomated manual radios, shall not be impaired by implementation of these automated features.

4.1 System test performance. Testing stations designed to this standard shall demonstrate an overall system performance equal to or exceeding the following requirement. Linking attempts made with a test setup configured as shown on Figure 1, using an ALE signal created in accordance with this standard, shall produce a probability of linking as shown in Table I.

The receive audio input to the ALE controller shall be used to simulate the three channel conditions. The CCIR good channel shall be characterized as having 0.5 millisecond (ms) multipath delay and a fading (two sigma) bandwidth of 0.1 Hz. The CCIR poor channel, normally characterized as consisting of a circuit having 2.0 ms multipath delay with a fading (two sigma) bandwidth of 1.0 Hz, shall be modified to have 2.2 ms multipath delay and a fading (two sigma) bandwidth of 1.0 Hz. Doppler shifts of -60 Hz for the CCIR good and poor channels (see Table I) shall produce no more than a 1.0 decibel (dB) performance degradation.

NOTE: This modification is necessary due to the fact that the constant 2-ms multipath delay (an unrealistic fixed condition) of the CCIR poor channel results in a constant nulling of certain tones of the ALE tone library.

Each of the signal-to-noise ratio (SNR) values shall be measured in a nominal 3-kHz bandwidth. Performance tests of this capability shall be conducted in accordance with CCIR Recommendation 520, "Use of High Frequency Ionospheric Channel Simulators," employing the C.C. Watterson Model. This test shall use the individual calling scanning protocol described in par. 5.3.4.3. The time for performance of each link attempt shall be measured from the initiation of the calling transmission until the successful establishment of the link. The time from initiation to establishment shall not exceed 14.000 seconds plus simulator delay time. Performance testing shall include the following additional criteria:

a. The protocol used shall be the individual calling scanning protocol with only TO and THIS IS preambles. Specifically, the call shall not exceed 23 T_rw, the Response, 3 T_rw, and the Acknowledgement, 3 T_rw.

b. Addresses used shall be alphanumeric, one word (3 characters) in length, from the 38-character basic American Standard Code for Information Interchange (ASCII) subset.

c. Units under test (UUTs) shall be scanning 10 channels at 2 channels per second.

d. Call initiation shall be performed with the UUT transmitter stopped and tuned to the calling frequency.

e. Maximum time from call initiation (measured from start of UUT radio frequency (rf) transmission, not from activation of the ALE protocol) to link establishment, shall not exceed 14.000 seconds, plus simulator delay time.

NOTE: Performance at the higher scan rates shall also meet the foregoing requirements and shall produce the same probability of linking as shown in Table I.

  Figure 1. System performance measurements test setup

TABLE I. Probability of linking

	Signal-to-Noise Ratio (dB)
Probability of Linking (Pl)	Gaussian Noise Channel	CCIR Good Channel	CCIR Poor Channel
25%	-2.5	+0.5	+1.0
50%	-1.5	+2.5	+3.0
85%	-0.5	+5.5	+6.0
95%	0.0	+8.5	+11.0

4.2 Channel memory. The equipment shall be capable of storing, retrieving, and employing at least 100 different sets of information concerning channel data to include receive and transmit frequencies with associated mode information. See Table II. The channel information storage shall be nonvolatile. The mode data shall include:

• sounding information
• group net association
• modulation type (associated with frequency)
• transmit/receive modes
• filter width (DO)
• automatic gain control (AGC) setting (DO)
• antenna selection (DO)
• input/output information port selection (DO)
• noise blanker setting (DO)
• receive and transmit subaudible tone selection (if narrow band frequency modulation (NBFM)) capable) (DO)
• transmit power level (DO)
• traffic or channel use (voice, data, etc.) (DO)
• security (DO)
• sounding self addresses (DO)

Any channel shall be capable of (1) being recalled manually and also under the direction of an automated controller if associated and (2) being altered after recall without affecting the original stored information settings.

  TABLE II. Channel memory example

• automatic controller input of stop scan (the normal mode of operation)
• manual input of stop scan
• activation of push-to-talk (PTT) line (DO)
• activation of external stop scan line (DO)

4.4 Self-address memory. The radio shall be capable of storing, retrieving, and employing at least 20 different sets of information concerning self-addressing. The self-address information storage shall be nonvolatile. These sets of information include self (its own personal) address(es), valid channels which are associated for use, and net addressing. Net addressing information shall include (for each "net member" self-address, as necessary) the net address and the present slot wait time T_swt (in multiples of wait time (T_w)). See Table III. The slot wait time values for each slot number are T_swt(SN) (slot number) from the formula in par. 5.3.6.2. Stations called by their net call address shall respond with their associated self (net member) address with the specified delay T_swt(SN). For example, the call is "GUY" thus the response is "BEN." Stations called individually by one of their self addresses (even if a net member address) shall respond immediately, and with that address, as specified in the individual (scanning) calling protocol. Stations called by one of their self addresses (even if a net member address) within a group call shall respond in the derived slot, and with that address, as specified in the star group (scanning) calling protocol. If a station is called by one of its net addresses and has no associated net member address, it shall pause and listen to the entire transmission but shall not respond (unless subsequently called separately with an available self or net member address).

4.5 Other address memory. The radio shall be capable of storing, retrieving, and employing at least 100 different sets of information concerning the addresses of other stations and nets. The other address information storage shall be nonvolatile. Individual addresses shall be stored individually and shall be associated with a specific wait for reply time (T_wr) if not the default value.

Net information shall include their net and net member associations, their relative slot sequences, and their net wait for reply times (T_wrn) for use when calling. See Table IV.

As a DO, any excess capacity which is not programmed with preplanned other address information should be automatically filled with any (transmitted) addresses heard on any of the scanned or monitored channels. When the excess capacity is filled, it should be kept current by replacing the oldest heard addresses with the latest ones heard. This fortuitous information should be used for calling initiation to those stations (if needed) and for activity evaluation.

4.6 Connectivity and LQA memory. The radio shall be capable of storing, retrieving, and employing at least 4000 (DO: 10,000) sets of connectivity and LQA information associated with the channels and the other addresses in an LQA memory. The connectivity and LQA information storage shall be nonvolatile. The information in each address/channel "cell" shall include as a minimum, the bilateral (two-way) bit error ratio (BER) values of (1) the signals received at the station and (2) the station's signals received at, and reported by, the other station. It shall also include either an indicator of the age of the information (for discounting old data), or an algorithm for automatically reducing the weight of data with time, to compensate for changing propagation conditions. As a DO, the cells of the LQA memory shall also include bilateral SINAD and multipath (MP) values derived by suitably equipped units. The information within the LQA memory shall be used to select channels and manage networks as stated in this document. See Figure 2.

  Figure 2. Connectivity and LQA matrix