# I could not find any information regarding the increase in bits in resolution for HiRes mode. Is there any information available?

### Question:

I could not find any information regarding the increase in bits in resolution for HiRes mode. Is there any information available?

The increase in bits in resolution depends on the decimation ratio.  The decimation ratio can be determined as follows:

D = MFs / Fs

MFs is the maximum non-interleaved sampling frequency of the scope.  For example: 5 GS/s for the DPO4104B or 2.5 GS/s for the DPO4014B models.  (Refer to the individual instrument's listed single channel sample rate.)

Fs is the sampling frequency that is displayed next to the time/div readout below the graticule.

The increase in bits over the original 8-bits of resolution is given by:
Enhanced Resolution Bits =  0.5 Log 2 ( D )

The table below therfore uses:
Bits of Resolution =  0.5 Log 2 ( D ) + 8

The HiRes smoothing algorithm performs a digital boxcar filter on the decimated acquisition, reducing its bandwidth.  The 3 dB bandwidth for HiRes mode is approximately 0.44 of the sample rate.

The following tables indicate the Bits of Resolution obtained for selected sample rates.  Note that the only reliable way for a customer to know what the bits of resolution and bandwidth are is by looking at the sample rate readout.  You cannot use time/div, since that varies the sample rate depending on the record length.

In order to make the table more usable by customers, we have used product sample rates, rather than using power-of-two decimation factors, which would be more precise.  For that reason, the table doesn’t follow a nice 1, 2.5, 5 sample rate ratio, because our goal was to find the closest power-of-two, in order to have it progress by bits of resolution.

HiRes example results at 5 GS/s base sample rate (e.g. DPO4104B)

 Sample Rate Bits of  Resolution 3 dB Bandwidth Limit (0.44 x Sample Rate) 2.5 GS/s 8.5 bits 1.1 GHz * 1 GS/s 9 bits 440 MHz 250 MS/s 10 bits 110 MHz 50 MS/s 11 bits 22 MHz 10 MS/s 12 bits 4.4 MHz 2.5 MS/s 13 bits 1.1 MHz 1 MS/s 14 bits 440 KHz 250 KS/s 15 bits 110 KHz 25 KS/s >15 bits 11 KHz 250 S/s >15 bits 110 Hz 25 S/s >15 bits 11 Hz 2.5 S/s >15 bits 1.1 Hz

HiRes example results at 2.5 GS/s base sample rate (e.g. DPO4014)

 Sample Rate Bits of  Resolution 3 dB Bandwidth Limit (0.44 x Sample Rate) 1.25 GS/s 8.5 bits 550 MHz * 500 MS/s 9 bits 220 MHz 100 MS/s 10 bits 44 MHz 25 MS/s 11 bits 11 MHz 5 MS/s 12 bits 2.2 MHz 1 MS/s 13 bits 440 KHz 500 KS/s 14 bits 220 KHz 100 KS/s 15 bits 44 KHz 25 KS/s >15 bits 11 KHz 250 S/s >15 bits 110 Hz 25 S/s >15 bits 11 Hz 2.5 S/s >15 bits 1.1 Hz

* The maximum HiRes bandwidth is further limited by the analog bandwidth.

This FAQ Applies to:

Product Series:

Product: DPO4054, DPO4034, DPO4032, DPO4104, MSO4032, MSO4034, MSO4054, MSO4104, MDO3012, MDO3014, MDO3022, MDO3024, MDO3032, MDO3034, MDO3052, MDO3054, MDO3102, MDO3104, MDO4014-3, MDO4014B-3, MDO4034-3, MDO4034B-3, MDO4054-3, MDO4054-6, MDO4054B-3, MDO4054B-6, MDO4104-3, MDO4104-6, MDO4104B-3, MDO4104B-6, MSO4014B, MSO4034B, MSO4054B, MSO4102B, MSO4102B-L, MSO4104B, MSO4104B-L, DPO4014B, DPO4034B, DPO4054B, DPO4102B, DPO4102B-L, DPO4104B, DPO4104B-L, MDO4024C, MDO4034C, MDO4054C, MDO4104C

FAQ ID : 55421

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