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Analog Data, Format 1 packets are used to record digitized analog signals. In general, the analog data packet will contain multiple digitized values from multiple analog channels. Digitized signal values can be stored in either a unpacked or packed fashion. Unpacked storage describes a situation in which each sample occupies one 16-bit word with unused bits zero filled. Packed storage concatenates samples to use the least amount of storage possible, but samples will straddle 16-bit word boundaries.

The layout of the CSDW is shown in Figure 6-31. Analog packets may have one or multiple CSDWs. If all analog subchannels are the same then the bSame value will equal “1” and only one CSDW will be present. If subchannels are configured differently then there will be one CSDW for each subchannel. The uMode field indicates the whether the samples are stored in packed or unpacked mode, and how unused bits are zero filled. The uLength field indicates the number of bits in digitized sample. The uSubChan field indicates the number of the current subchannel. The uTotChan field indicates the total number of subchannels in the packet. The uFactor field indicates the exponent of the power of 2 sampling rate factor denominator.

struct SuAnalogF1_ChanSpec 
    { 
    uint32_t    uMode       : 2;    // Packed or Unpacked 
    uint32_t    uLength     : 6;    // Bits in A/D value 
    uint32_t    uSubChan    : 8;    // Subchannel number 
    uint32_t    uTotChan    : 8;    // Total number of subchannels 
    uint32_t    uFactor     : 4;    // Sample rate exponent 
    uint32_t    bSame       : 1;    // One/multiple CSDW 
    uint32_t    iReserved   : 3;    // 
    }; 

Sample rate, Least Significant Bit (LSB) value, offset, and other analog parameters are recorded in the TMATS packet. The layout of the sequential samples is described in detail in the Chapter 10 standard

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