Difference between revisions of "NVGate DSP computation SPU"

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[[category:WikiOros]]
<!-- NVGate DSP Computation SPU — Wiki page -->
<!-- NVGate DSP Computation SPU — Wiki page -->


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💡 <strong>Key principle:</strong> The higher the sampling frequency, the more data to process — and the fewer SPUs are available per DSP board. SPU budget must be shared across all active channels and analysis types.
💡 <strong>Key principle:</strong> The higher the sampling frequency, the more data to process — and the fewer SPUs are available per DSP board. SPU budget must be shared across all active channels and analysis types.
</div>
</div>
= Force DSP=


<!-- ── DSP MODE OVERVIEW ────────────────────────────────── -->
{| style="width:100%;border-collapse:separate;border-spacing:10px;margin-bottom:8px;"
|-
| style="width:50%;background:#EEF4FF;border:2px solid #0057A8;border-radius:10px;padding:14px 18px;vertical-align:top;" |
<div style="font-family:Arial,sans-serif;font-weight:700;font-size:1em;color:#0057A8;margin-bottom:6px;">🔵 Normal DSP</div>
<div style="font-family:Arial,sans-serif;font-size:0.82em;color:#1A2340;">Models: OR34 V1 · OR35 V1 · OR36 V1/V2 · OR38 V1/V2<br/>Computation is <strong>linear</strong>: <strong>1 DSP = 12 SPU</strong>, regardless of sampling frequency.</div>
| style="width:50%;background:#FFF3E6;border:2px solid #F07800;border-radius:10px;padding:14px 18px;vertical-align:top;" |
<div style="font-family:Arial,sans-serif;font-weight:700;font-size:1em;color:#F07800;margin-bottom:6px;">🟠 Force DSP</div>
<div style="font-family:Arial,sans-serif;font-size:0.82em;color:#1A2340;">SPU count <strong>varies with sampling frequency</strong>. Higher frequency = fewer available SPUs. Force DSP generally requires <strong>2.5× to 5× fewer SPUs</strong> per channel than Normal DSP.</div>
|}


<!-- ── SPU AVAILABILITY (FORCE & NORMAL DSP) ──────────── -->
On force DSP (and normal DSP), the number of SPU change according to the max sampling frequency.
== 📊 SPU Availability vs. Sampling Frequency ==


<small style="font-family:Arial,sans-serif;color:#6B7A99;">Applies to both Force DSP and Normal DSP modes.</small>
The more you have data to analyse (high sampling frequency), the less you have power computation (SPU).
We have:


{| class="wikitable" style="width:50%;margin-top:8px;"
{| class="wikitable"
! Sampling Frequency (kHz) !! SPU per DSP board
|-
! Sampling Frequency (kHz) !! Number of SPU / DSP (Normal or Force)
|-
|-
| 102.4 || 6
| 102.4 || 6
Line 52: Line 46:
|}
|}


{{#widget:CalculateurSPU}}
===FFT===
According to the architecture of force DSP, the SPU computation per channels is not linear.  So we have the following table for real time SPU computation :


----
{| class="wikitable"
 
|-
<!-- ══════════════════════════════════════════════════════
! Number of FFT lines !! Normal DSP: SPU / channel !! Force DSP: SPU / channel
    FFT
══════════════════════════════════════════════════════ -->
== 🔬 FFT ==
 
<!-- Force DSP note -->
<div style="background:#FFF3E6;border-left:4px solid #F07800;border-radius:0 8px 8px 0;padding:8px 14px;margin-bottom:10px;font-family:Arial,sans-serif;font-size:0.82em;">
⚠️ <strong>Force DSP note:</strong> Computation is not linear. FFT 801 lines is the most optimised configuration. Envelope (401 lines) = 2 SPU/ch · Zoom (401 lines) = 0.66 SPU/ch.
</div>
 
{| class="wikitable" style="width:100%;"
! FFT Lines !! 🔵 Normal DSP (SPU/ch) !! 🟠 Force DSP (SPU/ch)
|-
|-
| 401 || 1 || 0.33
| 401 ||1 || 0.33
|-
|-
| 801 || 1.25 || 0.18 <sup>①</sup>
| 801 || 1.25 || 0.18 (yes<sup>1</sup>)
|-
|-
| 1 601 || 1.5 || 0.75
| 1601 || 1.5 || 0.75
|-
|-
| 3 201 || 2 || 0.8
| 3201 || 2 || 0.8
|-
|-
| 6 401 || 3 || 2
| 6401 || 3 || 2
|-
|-
| 12 801 || 4 || 2
| 12801 || 4 || 2
|-
|-
| 25 601 || 6 || 3.5
| 25601 || 6 || 3.5
|}
|}
<small style="font-family:Arial,sans-serif;color:#6B7A99;">① 801 lines is the most optimised resolution for Force DSP.</small>


<!-- Normal DSP FFT detail -->
Envelope: 401 lines : 2 SPU per channel on force DSP
<div style="background:#EEF4FF;border-left:4px solid #0057A8;border-radius:0 8px 8px 0;padding:10px 14px;margin-top:14px;margin-bottom:10px;font-family:Arial,sans-serif;font-size:0.82em;">
 
🔵 <strong>Normal DSP — bandwidth & options effect</strong> (401 lines, Fdec=1 as base)
Zoom: 401 Lines : 0.66 SPU per channel on force DSP.
</div>
 
1) Computing is not linear and FFT 801 lines is the most optimised for DSP
 
===Recorder===


{| class="wikitable" style="width:100%;"
{| class="wikitable"
! Bandwidth !! Fdec !! Resolution !! Envelope !! Zoom !! SPU/ch (real-time) !! SPU/ch (non real-time)
|-
|-
| 20 kHz || 1 || 401 || No || No || 1 || 0.5
! Recorder Sampling frequency (Hz) !! Normal DSP: SPU / channel !! Force DSP: SPU / channel
|-
|-
| 10 kHz || 1 || 401 || No || No || 0.5 || 0.25
| 51200 or upper || 1 || 0.66
|-
|-
| N kHz || 1 || 401 || No || No || = N/20 || = N/40
| 32768 || 0.66 || 0.44
|-
|-
| 10 kHz || 2 || 401 || No || No || 1 || 1
| 25600 || 0.5 || 0.33
|-
|-
| 5 kHz || 4 || 401 || No || No || 0.8 || 0.6
| 16384 || 0.33 || 0.22
|-
|-
| 2 kHz || 10 || 401 || No || No || 0.6 || 0.6
| 12800 || 0.25 || 0.167
|-
|-
| 1 kHz || 20 || 401 || No || No || 0.5 || 0.6
| Else || 0.125 || 0.083
|}
 
===Octave===
 
{| class="wikitable"
|-
! Octave !! Normal DSP: SPU / channel !! Force DSP: SPU / channel
|-
|-
| < 1 kHz || > 20 || 401 || No || No || 0.5 || 0.5
| 1/3 || 3 || 1
|-
|-
| 20 kHz || 1 || 801 || No || No || 1.25 || 0.5
| 1/12 || 6 || 2
|-
|-
| 20 kHz || 1 || 1 601 || No || No || 1.5 || 0.5
| 1/24 || 12 || 4
|}
 
===OVA===
 
{| class="wikitable"
|-
|-
| 20 kHz || 1 || 3 201 || No || No || 2 || 0.5
! Normal DSP: SPU / channel !! Force DSP: SPU / channel
|-
|-
| 20 kHz || 1 || 6 401 || No || No || 3 || 0.5
| 1 || 0.25
|}
 
===TDA===
 
 
{| class="wikitable"
|-
|-
| 20 kHz || 1 || 401 || No || Yes || 2 || 1.5
! Normal DSP: SPU / channel !! Force DSP: SPU / channel
|-
|-
| 20 kHz || 1 || 401 || Yes || Yes || 3 || 3
| 3 || 1.5
|}
|}


[[Image:fft_sampling.png|500px|none]]
===SOA===
 
SPU computation for SOA is more complex because it depends of maximum speed, resolution and frequency. Also force DSP computation is not linear.
 
Force DSP will improve the SPU computation by reducing between  2.5 and 5 to compare with normal DSP.
 
(@20kHz - 401 lines, we need a maximum of 3 SPUs with normal DSP)
 
= Normal DSP=
SPU computation for normal DSP : OR34 V1 - OR35V1 - OR36V1 OR36V2 (normal DSP) - OR38V1 - OR38V2 (Normal DSP).
 
Because of the computation linearity, we simplify by saying: 1DSP = 12 SPU (no matter the sampling frequency). This allow a simplification for SPU computation. So we can deduce:


----
==FFT==


<!-- ══════════════════════════════════════════════════════
'''Computation SPUs:'''
    RECORDER
══════════════════════════════════════════════════════ -->
== 🎙️ Recorder ==


<small style="font-family:Arial,sans-serif;color:#6B7A99;">Force DSP only.</small>
{|class="wikitable" style="background:white"border="2" cellspacing="0" cellpadding="4" width="85%" align="center"
|'''Bandwidth'''
|'''Fdec'''
|'''Resolution'''
|'''Envelope'''
|'''Zoom'''
|'''SPU/Channel <br>for Real-time'''
|'''SPU/Channel <br>for non Real-time'''


{| class="wikitable" style="width:70%;"
! Recorder Sampling Frequency (Hz) !! 🔵 Normal DSP (SPU/ch) !! 🟠 Force DSP (SPU/ch)
|-
|-
| ≥ 51 200 || 1 || 0.66
|20k
|1
|401
|No
|No
|1
|0,5
 
|-
|-
| 32 768 || 0.66 || 0.44
|10k
|1
|401
|No
|No
|0,5
|0,25
 
|-
|-
| 25 600 || 0.5 || 0.33
|Nk
|1
|401
|No
|No
|=N/20
|=N/40
 
|-
|-
| 16 384 || 0.33 || 0.22
|10k
|2
|401
|No
|No
|1
|1
 
|-
|-
| 12 800 || 0.25 || 0.167
|5k
|4
|401
|No
|No
|0,8
|0,6
 
|-
|-
| Other || 0.125 || 0.083
|2k
|}
|10
|401
|No
|No
|0,6
|0,6


----
|-
|1k
|20
|401
|No
|No
|0,5
|0,6


<!-- ══════════════════════════════════════════════════════
|-
    OCTAVE
|Lower <br>than 1k
══════════════════════════════════════════════════════ -->
|Higher <br>than 20
== 🎵 Octave ==
|401
|No
|No
|0,5
|0,5


'''Force DSP — summary:'''
|-
|20k
|1
|401 and<br>below
|No
|No
|1
|0,5


{| class="wikitable" style="width:50%;"
! Resolution !! 🔵 Normal DSP (SPU/ch) !! 🟠 Force DSP (SPU/ch)
|-
|-
| 1/3 oct || 3 || 1
|20k
|1
|801
|No
|No
|1,25
|0,5
 
|-
|-
| 1/12 oct || 6 || 2
|20k
|1
|1601
|No
|No
|1,5
|0,5
 
|-
|-
| 1/24 oct || 12 || 4
|20k
|}
|1
|3201
|No
|No
|2
|0,5


'''Normal DSP — full detail:'''
|-
|20k
|1
|6401
|No
|No
|3
|0,5


{| class="wikitable" style="width:70%;"
! Bandwidth !! Fdec !! Resolution !! SPU/ch (real-time)
|-
|-
| 25.6 kHz || 1 || 1/3 oct || 4
|20k
|1
|401
|No
|No
|1
|0,5
 
|-
|-
| 20 kHz || 1 || 1/3 oct || 3
|20k
|1
|401
|No
|Yes
|2
|1,5
 
|-
|-
| 12.8 kHz || 1 || 1/3 oct || 2
|20k
|1
|401
|No
|No
|1
|0,5
 
|-
|-
| 10 kHz || 1 || 1/3 oct || 1.5
|20k
|1
|401
|Yes
|Yes
|3
|3
 
|}<br clear="all">
 
 
[[Image:fft_sampling.png|500px|none]]
 
==SOA==
Computation SPUs:<br>
 
{|class="wikitable" style="background:white" border="2" cellspacing="0" cellpadding="4" width="79%" align="center"
|align = "center"|'''Bandwidth (Hz)'''
|align = "center"|'''Decimation factor'''
|align = "center"|'''Resolution'''
|align = "center"|'''SPU/Channel'''
 
|-
|-
| 10 kHz || 2 || 1/3 oct || 2
|align = "center"|20 k
|align = "center"|1
|align = "center"|401
|align = "center"|3
 
|-
|-
| 5 kHz || 4 || 1/3 oct || 1.25
|align = "center"|10 k
|align = "center"|1
|align = "center"|401
|align = "center"|1,5
 
|-
|-
| 20 kHz || 1 || 1/1 oct || 1.5
|align = "center"|N k
|align = "center"|1
|align = "center"|401
|align = "center"|=(N*3)/20
 
|-
|-
| 20 kHz || 1 || 1/12 oct || 6
|align = "center"|10 k
|align = "center"|2
|align = "center"|401
|align = "center"|2
 
|-
|-
| 20 kHz || 1 || 1/24 oct || 12
|align = "center"|5 k
|}
|align = "center"|4
|align = "center"|401
|align = "center"|1,3


<small style="font-family:Arial,sans-serif;color:#6B7A99;">Sampling Frequency: ''Front-End / Inputs settings / Input sampling'' · Bandwidth: ''OCT / FFT analysis / range''</small>
|-
|align = "center"|2,5 k
|align = "center"|8
|align = "center"|401
|align = "center"|1,1


[[Image:Octave_01.png|framed|none]]
|-
|align = "center"|1,25 k
|align = "center"|16
|align = "center"|401
|align = "center"|0,9


----
|-
|align = "center"|625
|align = "center"|32
|align = "center"|401
|align = "center"|0,8


<!-- ══════════════════════════════════════════════════════
|-
    OVA
|align = "center"|313
══════════════════════════════════════════════════════ -->
|align = "center"|64
== 📈 OVA (Overall Acoustic Levels) ==
|align = "center"|401
|align = "center"|0,7


'''Force DSP:'''
|-
|align = "center"|156
|align = "center"|128
|align = "center"|401
|align = "center"|0,6


{| class="wikitable" style="width:40%;"
! 🔵 Normal DSP (SPU/ch) !! 🟠 Force DSP (SPU/ch)
|-
|-
| 1 || 0.25
|align = "center"|78
|}
|align = "center"|256
|align = "center"|401
|align = "center"|0,6


'''Normal DSP — by bandwidth:'''
|-
|align = "center"|20 k
|align = "center"|1
|align = "center"|401 and below
|align = "center"|3


{| class="wikitable" style="width:50%;"
! Bandwidth !! SPU/ch (real-time)
|-
|-
| 25.6 kHz || 1.25
|align = "center"|20 k
|-
|align = "center"|1
| 20 kHz || 1
|align = "center"|801
|-
|align = "center"|3,25
| 12.8 kHz || 0.75
 
|-
|}<br clear="all">
| 10 kHz || 0.5
|}


<small style="font-family:Arial,sans-serif;color:#6B7A99;">SPU count is directly proportional to analysis bandwidth (sampling frequency ÷ 2.56).</small>
[[Image:Order_analysis_19.png|framed|none]]


----
Sampling Frequency: set in ''Front-End/Inputs settings/Input sampling''


<!-- ══════════════════════════════════════════════════════
FFT Bandwidth: set in ''FFTx/FFT analysis/range''
    TDA
══════════════════════════════════════════════════════ -->
== ⏱️ TDA ==


{| class="wikitable" style="width:40%;"
==
! 🔵 Normal DSP (SPU/ch) !! 🟠 Force DSP (SPU/ch)
|-
| 3 || 1.5
|}


----
==Octave:==


<!-- ══════════════════════════════════════════════════════
{|class="wikitable" style="background:white" border="2" cellspacing="0" cellpadding="4" width="61%" align="center"
    SOA
|'''Bandwidth'''
══════════════════════════════════════════════════════ -->
|'''Fdec'''
== 🔄 SOA (Order Analysis) ==
|'''Reso'''
|'''SPU/Channel <br>for Real-time'''


<div style="background:#FFF3E6;border-left:4px solid #F07800;border-radius:0 8px 8px 0;padding:8px 14px;margin-bottom:12px;font-family:Arial,sans-serif;font-size:0.82em;">
|-
⚠️ SOA computation depends on <strong>maximum speed, resolution and frequency</strong>. Force DSP computation is non-linear and reduces SPU consumption by <strong>2.5× to 5×</strong> vs Normal DSP.<br/>
|25.6k
<em>Example: @20 kHz, 401 lines → max 3 SPU/ch with Normal DSP.</em>
|1
</div>
|1/3rd
|4


'''Normal DSP — SOA detail:'''
|-
|20k
|1
|1/3rd
|3


{| class="wikitable" style="width:70%;"
! Bandwidth (Hz) !! Decimation !! Resolution !! SPU/ch
|-
|-
| 20 kHz || 1 || 401 || 3
|12.8k
|1
|1/3rd
|2
 
|-
|-
| 10 kHz || 1 || 401 || 1.5
|10k
|1
|1/3rd
|1,5
 
|-
|-
| N kHz || 1 || 401 || = (N × 3) / 20
|20k
|1
|1/3rd
|3,0
 
|-
|-
| 10 kHz || 2 || 401 || 2
|10k
|2
|1/3rd
|2,0
 
|-
|-
| 5 kHz || 4 || 401 || 1.3
|5k
|4
|1/3rd
|1,25
 
|-
|-
| 2.5 kHz || 8 || 401 || 1.1
|20k
|1
|1/1
|1,5
 
|-
|-
| 1.25 kHz || 16 || 401 || 0.9
|20k
|1
|1/3rd
|3
 
|-
|-
| 625 Hz || 32 || 401 || 0.8
|20k
|1
|1/12th
|6
 
|-
|-
| 313 Hz || 64 || 401 || 0.7
|20k
|1
|1/24th
|12
 
|}<br clear="all">
 
[[Image:Octave_01.png|framed|none]]
 
Sampling Frequency: set in ''Front-End/Inputs settings/Input sampling''
 
1/N Oct Bandwidth: set in ''OCT/FFT analysis/range''
 
==OVA==
 
{|class="wikitable" style="background:white" border="2" cellspacing="0" cellpadding="4" width="52%"
|align = "center"|'''Bandwidth'''
|align = "center"|'''SPU/Channel <br>for Real-time'''
 
|-
|-
| 156 Hz || 128 || 401 || 0.6
|align = "center"|25,6k
|align = "center"|1,25
 
|-
|-
| 78 Hz || 256 || 401 || 0.6
|align = "center"|20k
|align = "center"|1
 
|-
|-
| 20 kHz || 1 || 801 || 3.25
|align = "center"|12,8k
|}
|align = "center"|0,75


<small style="font-family:Arial,sans-serif;color:#6B7A99;">Sampling Frequency: ''Front-End / Inputs settings / Input sampling'' · FFT Bandwidth: ''FFTx / FFT analysis / range''</small>
|-
|align = "center"|10k
|align = "center"|0,5


[[Image:Order_analysis_19.png|framed|none]]
|}


[[Category:WikiOros]]
The overall acoustic levels analysis requires 1 SPU per channel at 20 kHz bandwidth. The number of required SPUs is directly proportional to the analysis bandwidth (i.e. the sampling frequency divided by 2.56).

Latest revision as of 10:10, 2 April 2026


⚙️ NVGate — DSP Computation SPU
Reference tables for Signal Processing Unit (SPU) consumption per channel and per analysis type.

💡 Key principle: The higher the sampling frequency, the more data to process — and the fewer SPUs are available per DSP board. SPU budget must be shared across all active channels and analysis types.

Force DSP

On force DSP (and normal DSP), the number of SPU change according to the max sampling frequency.

The more you have data to analyse (high sampling frequency), the less you have power computation (SPU). We have:

Sampling Frequency (kHz) Number of SPU / DSP (Normal or Force)
102.4 6
65.536 9
51.2 12
32.768 18
25.6 24
16.384 36
12.8 48
6.4 96
3.2 192
1.6 384

FFT

According to the architecture of force DSP, the SPU computation per channels is not linear. So we have the following table for real time SPU computation :

Number of FFT lines Normal DSP: SPU / channel Force DSP: SPU / channel
401 1 0.33
801 1.25 0.18 (yes1)
1601 1.5 0.75
3201 2 0.8
6401 3 2
12801 4 2
25601 6 3.5

Envelope: 401 lines : 2 SPU per channel on force DSP

Zoom: 401 Lines : 0.66 SPU per channel on force DSP.

1) Computing is not linear and FFT 801 lines is the most optimised for DSP

Recorder

Recorder Sampling frequency (Hz) Normal DSP: SPU / channel Force DSP: SPU / channel
51200 or upper 1 0.66
32768 0.66 0.44
25600 0.5 0.33
16384 0.33 0.22
12800 0.25 0.167
Else 0.125 0.083

Octave

Octave Normal DSP: SPU / channel Force DSP: SPU / channel
1/3 3 1
1/12 6 2
1/24 12 4

OVA

Normal DSP: SPU / channel Force DSP: SPU / channel
1 0.25

TDA

Normal DSP: SPU / channel Force DSP: SPU / channel
3 1.5

SOA

SPU computation for SOA is more complex because it depends of maximum speed, resolution and frequency. Also force DSP computation is not linear.

Force DSP will improve the SPU computation by reducing between 2.5 and 5 to compare with normal DSP.

(@20kHz - 401 lines, we need a maximum of 3 SPUs with normal DSP)

Normal DSP

SPU computation for normal DSP : OR34 V1 - OR35V1 - OR36V1 OR36V2 (normal DSP) - OR38V1 - OR38V2 (Normal DSP).

Because of the computation linearity, we simplify by saying: 1DSP = 12 SPU (no matter the sampling frequency). This allow a simplification for SPU computation. So we can deduce:

FFT

Computation SPUs:

Bandwidth Fdec Resolution Envelope Zoom SPU/Channel
for Real-time 		SPU/Channel
for non Real-time
20k 1 401 No No 1 0,5
10k 1 401 No No 0,5 0,25
Nk 1 401 No No =N/20 =N/40
10k 2 401 No No 1 1
5k 4 401 No No 0,8 0,6
2k 10 401 No No 0,6 0,6
1k 20 401 No No 0,5 0,6
Lower
than 1k 		Higher
than 20 		401 No No 0,5 0,5
20k 1 401 and
below 		No No 1 0,5
20k 1 801 No No 1,25 0,5
20k 1 1601 No No 1,5 0,5
20k 1 3201 No No 2 0,5
20k 1 6401 No No 3 0,5
20k 1 401 No No 1 0,5
20k 1 401 No Yes 2 1,5
20k 1 401 No No 1 0,5
20k 1 401 Yes Yes 3 3



Fft sampling.png

SOA

Computation SPUs:

Bandwidth (Hz) Decimation factor Resolution SPU/Channel
20 k 1 401 3
10 k 1 401 1,5
N k 1 401 =(N*3)/20
10 k 2 401 2
5 k 4 401 1,3
2,5 k 8 401 1,1
1,25 k 16 401 0,9
625 32 401 0,8
313 64 401 0,7
156 128 401 0,6
78 256 401 0,6
20 k 1 401 and below 3
20 k 1 801 3,25


Order analysis 19.png

Sampling Frequency: set in Front-End/Inputs settings/Input sampling

FFT Bandwidth: set in FFTx/FFT analysis/range

==

Octave:

Bandwidth Fdec Reso SPU/Channel
for Real-time
25.6k 1 1/3rd 4
20k 1 1/3rd 3
12.8k 1 1/3rd 2
10k 1 1/3rd 1,5
20k 1 1/3rd 3,0
10k 2 1/3rd 2,0
5k 4 1/3rd 1,25
20k 1 1/1 1,5
20k 1 1/3rd 3
20k 1 1/12th 6
20k 1 1/24th 12


Octave 01.png

Sampling Frequency: set in Front-End/Inputs settings/Input sampling

1/N Oct Bandwidth: set in OCT/FFT analysis/range

OVA

Bandwidth SPU/Channel
for Real-time
25,6k 1,25
20k 1
12,8k 0,75
10k 0,5

The overall acoustic levels analysis requires 1 SPU per channel at 20 kHz bandwidth. The number of required SPUs is directly proportional to the analysis bandwidth (i.e. the sampling frequency divided by 2.56).

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