Sec. 97.311  SS emission types.

    (a) SS emission transmissions by an amateur station are authorized 
only for communications between points within areas where the amateur 
service is regulated by the FCC. SS emission transmissions must not be 
used for the purpose of obscuring the meaning of any communication.
    (b) Stations transmitting SS emission must not cause harmful 
interference to stations employing other authorized emissions, and must 
accept all interference caused by stations employing other authorized 
emissions. For the purposes of this paragraph, unintended triggering of 
carrier operated repeaters is not considered to be harmful interference.
    (c) Only the following types of SS emission transmissions are 
authorized (hybrid SS emissions transmissions involving both spreading 
techniques are prohibited):
    (1) Frequency hopping where the carrier of the transmitted signal is 
modulated with unciphered information and changes frequency at fixed 
intervals under the direction of a high speed code sequence.
    (2) Direct sequence where the information is modulo-2 added to a 
high speed code sequence. The combined information and code are then 
used to modulate the RF carrier. The high speed code sequence dominates 
the modulation function, and is the direct cause of the wide spreading 
of the transmitted signal.
    (d) The only spreading sequences that are authorized are from the 
output of one binary linear feedback shift register (which may be 
implemented in hardware or software).
    (1) Only the following sets of connections may be used:

------------------------------------------------------------------------
   Number of stages in shift register         Taps used in feedback     
------------------------------------------------------------------------
7......................................  7,1.                           
13.....................................  13,4, 3, and 1.                
19.....................................  19, 5, 2, and 1.               
------------------------------------------------------------------------

    (2) The shift register must not be reset other than by its feedback 
during an individual transmission. The shift register output sequence 
must be used without alteration.
    (3) The output of the last stage of the binary linear feedback shift 
register must be used as follows:
    (i) For frequency hopping transmissions using x frequencies, n 
consecutive bits from the shift register must be used to select the next 
frequency from a list of frequencies sorted in ascending order. Each 
consecutive frequency must be selected by a consecutive block of n bits. 
(Where n is the smallest integer greater than log2 x.)
    (ii) For direct sequence transmissions using m-ary modulation, 
consecutive blocks of log2 m bits from the shift register 
must be used to select the transmitted signal during each interval.
    (e) The station records must document all SS emission transmissions 
and must be retained for a period of 1 year following the last entry. 
The station records must include sufficient information to enable the 
FCC, using the information contained therein, to demodulate all 
transmissions. The station records must contain at least the following:
    (1) A technical description of the transmitted signal;
    (2) Pertinent parameters describing the transmitted signal including 
the frequency or frequencies of operation and, where applicable, the 
chip rate, the code rate, the spreading function, the transmission 
protocol(s) including the method of achieving sychronization, and the 
modulation type;
    (3) A general description of the type of information being conveyed, 
(voice, text, memory dump, facsimile, television, etc.);
    (4) The method and, if applicable, the frequency or frequencies used 
for station identification; and
    (5) The date of beginning and the date of ending use of each type of 
transmitted signal.
    (f) When deemed necessary by an EIC to assure compliance with this 
part, a station licensee must:
    (1) Cease SS emission transmissions;
    (2) Restrict SS emission transmissions to the extent instructed; and
    (3) Maintain a record, convertible to the original information 
(voice, text, image, etc.) of all spread spectrum communications 
transmitted.

[[Page 702]]

    (g) The transmitter power must not exceed 100 W.