HNT coverts to Data Credits at a rate pegged to
$.00001 , and so the blockchain requires a canonical HNT/$USD price for this conversion. Beginning in June 2020, the Helium blockchain started using a system of decentralized price oracles to supply the $USD to HNT price used for on-chain for burn transactions. (This system is inspired by the Maker Foundation's Oracle usage.)
To find this price, nine oracles (this number may change in the future) periodically submit HNT/$USD prices. Once the blockchain has enough new price data, it will calculate a new HNT/$USD price that will remain valid until enough new, valid oracle inputs are submitted, triggering a new price revision.
10 blocks (roughly every 10 minutes) the blockchain will attempt to establish a new HNT/$USD price. To do this:
The blockchain looks for recent price submissions from valid Oracles (submitted using a new transaction called
price_oracle_submission). A valid price submission is anything that was submitted within the last 25 hours but is older than 1 hour. This gives us the ability to calculate a trailing 24 hour median while also having a buffer against outlier price inputs in the most recent 60 minutes.
If there are enough new, valid price submissions in the 24 hour window, a new price will be calculated. For this to happen, a majority of the price Oracles need to have submitted a price in the window -
((N / 2) +1 ). So, in our system of
9 Oracles, we would need valid prices from at least
5. (If there aren’t
((N / 2) +1 ) new prices, no new HNT price is calculated.)
If there are at least
5 new prices, we then proceed to sort order the list low to high, and take the median. So, if we had
7 valid submissions of
$.45, the blockchain would select
$.238, and use this as the external price of HNT for all HNT / DC burn transactions until a new price is established (which could be as soon as
The HNT Oracle price feeds are supplied by a group of nine (9) Oracles, composed of companies, organizations, and individuals. They are:
Decentralized Wireless Alliance (DEWI)
Seven (7) Anonymous Individual Community Members
We’ve chosen to keep the names of the individual feed contributors anonymous as it’s essential to prevent any external attempts at extortion or blackmail. The names of large companies and organizations that supply feeds, however, are public and it’s easier for them to combat potential attacks and bad actors.
The current set of public keys for the nine HNT Price Oracles are (in no particular order):
Currently Oracles use the Helium Wallet CLI for submitting prices to the blockchain. Download this and get comfortable with it on your machine if you're not using it already.
We've added a new transaction to the blockchain for Oracle price submissions -
price_oracle_submission added a corresponding CLI command -
When you download the CLI and run
helium-wallet oracle report --help, here's what you'll see (as of version
helium-wallet-oracle-report 1.2.8Construct an oracle price report and optionally commit it to the Helium BlockchainUSAGE:helium-wallet oracle report [FLAGS] --block <block> --price <price>FLAGS:--commit Commit the oracle price report to the API-h, --help Prints help information-V, --version Prints version informationOPTIONS:--block <block> Block height to report the price at. Use "auto" to pick the latest known block height fromthe API--price <price> The oracle price to report. Specify in USD or supply one of the supported price lookupservices ("coingecko", "bilaxy")
Here's a full command to submit a price (with the leading
$ the command line will supply):
$ helium-wallet oracle report --price 1.1 --block auto --commit
This is telling the blockchain you are reporting a price of
$1.1 and the current block height and that you're ready to commit it.
Once you hit
Return, you'll be asked to input your wallet key passphrase. Supply this, submit it, and you're done.
All data from HNT price oracles is available via the Oracle Price Reports API.