InterDigital Communications Corp, King of Prussia, Pennsylvania maker of digital radio telephone systems, looks to raise $33m with the sale of units consisting of one share plus a warrant for another half share, to an undisclosed investor over the next 18 months. The purchaser has agreed to buy up to $80m more units over the following four years, subject to Interdigital’s agreement; the price of each unit will be 89% of the price of Interdigital stock at pre-set points. The buyer can exercise the warrants one year after they are issued for the next five and a half years, at a 5% premium to the closing price of the shares on the relevant dates.