Converting signed 14-bit sample codes to volts Sample Clauses

Converting signed 14-bit sample codes to volts. A signed code of 0 represents ~0V input voltage, 8191 (0x1FFF) represents a positive full-scale input voltage, and –8192 (0x2000) represents a negative full-scale input voltage. The following table illustrates how signed 14-bit sample codes map to values in volts depending on the full-scale input range of the input channel. Sample code in decimal Sample code in hex Sample value as a percentage of full- scale input range Sample value in volts if full-scale input range is Sample value in volts if full- scale input ±100 mV range is ±1 V -8191 0x2001 -100% -100 mV -1 V -4096 0x3000 -50% -50 mV -.5 V 0 0x0000 0% 0 V 0V 4096 0x1000 +50% 50 mV +.5 V 8191 0x1FFF +100% +100 mV +1 V The following code fragment demonstrates how to convert a 2-byte sample value containing a signed 14-bit sample code to in volts. double SampleToVoltsU14(U16 sampleValue, double inputRange_volts) { // Right-shift 16-bit sample word by 2 to get 14-bit sample code int bitShift = 2; U16 sampleCode = sampeWord >> bitShift; // AlazarTech digitizers are calibrated as follows int bitsPerSample = 14; double codeZero = (1 << (bitsPerSample - 1)) - 0.5; double codeRange = (1 << (bitsPerSample - 1)) - 0.5; // Convert the signed code to unsigned sampleCode = (sampleCode + 0x2000) & 0x1FFF; // Convert sample code to volts double sampleVolts = inputRange_volts * ((double) (sampleCode - codeZero) / codeRange); return sampleVolts; }