Typical Packet sizes & Data Cost of a IoT monitor? - Why choose Hologram?


#1

Hi there this is a general question about how other people are doing their projects, in particular;

Frequency of sampling data
Typical packet size of transmission

I’ve built a prototype that sends to around 10 channels every 10 minutes packet size range from 11 to 20kb, but on average ate 16 kb.

I’ve also done some calcs;

Where I’m based in Peru costs is $0.85 / MB

So cost per kb = 0.85 / 1024 = $0.00083 (assumption 1024 kb in a MB)

Posts per hour = 6
Number of posts per day = 6 * 24 = 144
cost per day = 144 * 0.00083 * 16kb = $1.91
Project Monthly cost = $57,37 + 0.40 for monthly charges

I must be doing something really inefficent with the data, as this is not financially viable, why would anyone use a pay per MB sim? Even if I reduce my transmissions to once an hour my calcs give $9.56

I’d really like to hear about your projects, how often you send, and the size of your data packets. I appreciate I must be doing something wrong in my prototype as my costs don’t make sense.

Background on my project: Arduino Uno with 6 Analogue inputs, connected to a Raspberry Pi, running Node Red to calculate average values, and transmit to the web via a 3G modem dongle, data being sent to ThingSpeak.com account


#2

Hi @windaid - Can you explain a bit more about the transit protocol for how you’re sending the packets? Is it something based on REST HTTP? From your notes it appears that each month you’d be expecting each device to send about 67 MB of data which definitely sounds high for the amount of actual payload info you’re sending.

Also including a bit more context here that I posted in your other post:

The data usage for each cellular session includes all traffic passed over the network including overhead so depending on how the data transmissions are passed from your application 11-20kb to send a payload of a float number value is possible as you’re seeing. A lighter-weight method of sending data via our Python SDK is an included benefit when transmitting over cellular. From there, our Data Engine allows you to route data over webhook or is retrievable via API.

For reference, here’s an older article describing in detail the difference in overhead between a protocol like REST HTTP vs. our Dash hardware (which would be similar to our Python SDK use). Hologram.io data usage breakdown

Definitely still interested to hear how others are managing their message intervals and protocols when every byte counts in cellular.

-Ryan


#3

Hi @ryanHologram

I’m afraid I can’t give you much of a technical answer about the transfer protocol. I’m using this node from Node RED to send to the thingspeak channel;

Thanks for the alternative suggestion of using Python SDK, I’ll take a more detailed look into it, but I’m about to field deploy this device next week. If I can’t get the data costs down, I’ll be using a standard SIM from one of the big networks as its significantly cheaper than Hologram on a MB basis, rather than rewrite my entire project in Python.

I’ll check out the other article also. Thanks very much for responding to my messages, it’s appreciated.